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A 49-year-old woman presents with a mass in her left breast. She says she discovered the mass during a monthly self-examination 3 months ago and has been 'watching it' since that time. She believes the mass has enlarged since she first discovered it. The patient denies any ulceration, weight loss, fatigue, night sweats, or nipple discharge. Her past medical history is significant for mild osteoporosis, managed with alendronate. The patient is afebrile, and her vital signs are within normal limits. On physical examination, there is a 4-mm-diameter left breast mass that is firm and non-tender on palpation. A mammogram of the left breast is performed but fails to display the mass. Which of the following is the best next step in the management of this patient?

Perform an ultrasound of the left breast

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E

A 28-year-old female presents to her primary care doctor complaining of new onset blurry vision. She first noticed her vision getting blurry toward the end of the day several days ago. Since then, she reports that her vision has been fine when she wakes up but gets worse throughout the day. She has also noticed that her eyelids have started to droop before she goes to bed. On exam, she has bilateral ptosis that is worse on the right. Administering edrophonium to this patient leads to an immediate improvement in her symptoms. Which of the following is most likely true about this patient’s condition?

It is associated with a benign proliferation of epithelial cells of the thymus

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B

A 62-year-old woman comes to the physician for a follow-up examination after a recent change in her medication regimen. She reports that she feels well. She has type 2 diabetes mellitus, hyperlipidemia, hypertension, essential tremor, and chronic back pain. Current medications are metformin, glyburide, propranolol, simvastatin, ramipril, amitriptyline, and ibuprofen. Fingerstick blood glucose concentration is 47 mg/dL. Serum studies confirm this value. Which of the following pharmacologic mechanisms is most likely responsible for the absence of symptoms in this patient?

Antagonism at β2-adrenergic receptors

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C

A 26-year-old woman presents to the clinic with complaints of missing her 'monthlies'. She usually has her menses are around the 15th of every month and they last for about 4 days. She is not on any birth control and has recently gotten into a relationship with a boy from college. She is on lithium for maintenance therapy of her bipolar disorder. She once took herself off of lithium, but she became so depressed that she had a suicide attempt shortly after. She is concerned about how lithium use might affect her fetus if she were pregnant. What is the single most appropriate recommendation?

Continue her lithium monotherapy.

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A

A 31-year-old woman comes to the physician because she thinks that her “right wrist is broken.” She says that she has severe pain and that “the bone is sticking out.” She has not had any trauma to the wrist. Her medical records indicate that she was diagnosed with schizophrenia 2 years ago and treated with olanzapine; she has not filled any prescriptions over the past 4 months. Three weeks ago, she stopped going to work because she “did not feel like getting up” in the morning. Vital signs are within normal limits. Physical examination of the right wrist shows no visible injury; there is no warmth, swelling, or erythema. Range of motion is limited by pain. On mental status examination, she has a flat affect. Her speech is pressured and she frequently changes the topic. She has short- and long-term memory deficits. Attention and concentration are poor. There is no evidence of suicidal ideation. Urine toxicology screening is negative. An x-ray of the wrist shows no abnormalities. Which of the following is the most appropriate response to this patient's concerns?

“I cannot see any injury of your wrist and the physical exam as well as the x-ray don't show any injury. I imagine that feeling as if your wrist was broken may be very uncomfortable. Can you tell me more about what it feels like?”

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A

A 62-year-old male presents to his primary care physician complaining of a chronic cough. He reports a six-month history of progressively worsening cough and occasional hemoptysis. He has lost ten pounds over the same time frame. His medical history is notable for hypertension, hyperlipidemia, and diabetes mellitus. He has a 50-pack-year smoking history. A chest radiograph reveals a coin-like central cavitary lesion. Tissue biopsy demonstrates findings consistent with squamous cell carcinoma. The patient is referred to a pulmonologist who starts the patient on a chemotherapeutic drug. However, after several weeks on the drug, the patient develops sensorineural hearing loss. Which of the following mechanisms of action is consistent with the most likely medication prescribed in this case?

Platinum-based DNA crosslinker

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E

A 35-year-old man comes to the physician because of an ulcer on his penis that he first noticed 4 days ago. He is currently sexually active with multiple male partners and uses condoms inconsistently. Genital examination shows a shallow, nontender ulcer with a smooth base and indurated border along the shaft of the penis. There is bilateral inguinal lymphadenopathy. Darkfield microscopy of a sample from the lesion shows gram-negative, spiral-shaped bacteria. A drug that acts by inhibition of which of the following is the most appropriate treatment for this patient?

Transpeptidase

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A

A 65-year-old man comes to the physician for a follow-up examination. He has chronic obstructive pulmonary disease and was recently discharged from the hospital for an exacerbation. His cough and chills have since improved, but his mobility is still severely limited by dyspnea and fatigue. He smoked 2 packs of cigarettes daily for 30 years, but quit 5 years ago. His medications include inhaled daily budesonide, formoterol, and tiotropium bromide plus ipratropium/albuterol as needed. Pulmonary function testing shows an FEV1 of 27% of predicted. Resting oxygen saturation ranges from 84–88%. Which of the following steps in management is most likely to increase the chance of survival in this patient?

Oxygen therapy

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D

A 52-year-old woman presents to her primary care provider with colicky left flank pain that radiates to her groin. She appears to be in significant distress and is having trouble getting comfortable on the exam table. She and her mother both have a history of calcium oxalate kidney stones. She has a past medical history significant for type 2 diabetes and hypertension. She takes metformin, metoprolol and lisinopril. She has been watching her weight and eating a high protein diet that mainly consists of chicken and seafood. She also eats a great deal of yogurt for the calcium. She asks if she should cut out the yogurt, and wonders if it is the cause of her current kidney stone. What lifestyle modification would reduce her risk of developing kidney stones in the future?

Decrease protein intake

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E

A 44-year-old man is brought to the clinic by his wife insisting that her husband has been acting strange lately. He is a dentist by profession and has no known medical conditions. For the past 6 weeks, he has insisted on listening to the 6 PM news on the radio. He is adamant that the news anchor is referencing his life during the broadcasts. Apart from this, his wife states that her husband is fine. He and his wife deny the use of any prescribed medications or illicit drugs. He is a non-smoker and drinks alcohol only on social occasions. Physical examination and routine laboratory investigations are normal. What is the most likely diagnosis?

Delusion of reference

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E

A 26-year-old female presents to the emergency department with high fever, productive cough, and hemoptysis. She says that she has also been getting red tender bumps under the skin as well as joint pain. She believes that her symptoms started a few days after a small earthquake hit near her hometown and was otherwise healthy prior to these symptoms. No pathogenic bacteria are detected on sputum culture or by Gram stain. Based on clinical suspicion a lung biopsy is performed and the results are shown in the image provided. The most likely pathogen causing this disease lives in which of the following locations?

Desert dust and sand

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B

During the obstetric clerkship, the doctor is observing a 3rd-year resident assist a delivery. The patient only had 1 prenatal ultrasound that reported a male fetus. The delivery progresses without complications. The pediatrician-in-charge of the newborn notices a short, broad, upturned penis with an orifice in its dorsal aspect, and both testicles are present in the scrotum. Both the attending and PGY-3 resident immediately recognize the condition. Which of the following female anatomical structures is derived from the embryonic structure affected in this patient?

Clitoris

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E

A 45-year-old woman comes to the physician because of a 4-month history of irritability and frequent bowel movements. During this time, she has had a 6.8-kg (15-lb) weight loss. She has not had a change in appetite or diet. She takes no medications. Her temperature is 37.4°C (99.4°F), pulse is 112/min, respirations are 16/min, and blood pressure is 126/74 mm Hg. Examination shows moist palms. The thyroid gland is diffusely enlarged; there are no palpable nodules. Serum studies show a thyroid-stimulating hormone (TSH) concentration of 0.2 μU/mL, thyroxine (T4) concentration of 22 μg/dL, and antibodies against the TSH receptor. Which of the following treatment modalities is associated with the lowest rate of recurrence for this patient's condition?

Radioactive iodine ablation

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B

A 50-year-old man presents to the emergency department for evaluation of a pulsatile headache, palpitations, chest pain, and anxiety. The vital signs include: heart rate 90/min, blood pressure 211/161 mm Hg, and respiration rate 18/min. His fundoscopic exam is remarkable for papilledema. An urgent urinalysis reveals increased protein and red blood cells (RBCs). Further evaluation reveals elevated plasma metanephrines. What is the 1st step in the definitive treatment of this patient’s underlying disorder?

Alpha-blockers followed by beta-blockers

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B

A 5-month-old boy is brought to the emergency department by his mother because his lips turned blue for several minutes while playing earlier that evening. She reports that he has had similar episodes during feeding that resolved quickly. He was born at term following an uncomplicated pregnancy and delivery. He is at the 25th percentile for length and below the 5th percentile for weight. His temperature is 37°C (98.6°F), pulse is 130/min, blood pressure is 83/55 mm Hg, and respirations are 42/min. Pulse oximetry on room air shows an oxygen saturation of 90%. During the examination, he sits calmly in his mother's lap. He appears well. The patient begins to cry when examination of his throat is attempted; his lips and fingers begin to turn blue. Further evaluation of this patient is most likely to show which of the following?

Right axis deviation on ECG

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B

A 65-year-old woman comes to the physician because of progressive weight loss for 3 months. Physical examination shows jaundice and a nontender, palpable gallbladder. A CT scan of the abdomen shows an ill-defined mass in the pancreatic head. She is scheduled for surgery to resect the pancreatic head, distal stomach, duodenum, early jejunum, gallbladder, and common bile duct and anastomose the jejunum to the remaining stomach, pancreas, and bile duct. Following surgery, this patient is at the greatest risk for which of the following?

Microcytic anemia

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B

A 25-year-old G1P0 woman at 14 weeks estimated gestational age presents for prenatal care. She has no complaints. No significant past medical history. The patient is afebrile and vital signs are within normal limits. Physical examination is unremarkable. Laboratory findings are significant for the following: Thyroid-stimulating hormone (TSH) 0.3 mIU/L (0.4–4.2 mIU/L) Total T4 11.4 µg/dL (5.4–11.5 µg/dL) Free total T4 0.7 ng/dL (0.7–1.8 ng/dL) Which of the following is the most likely etiology of this patient’s laboratory findings?

Estrogen regulation of thyroxine-binding globulin secretion (TBG)

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A

A 50-year-old female is evaluated by her physician for recent weight gain. Physical examination is notable for truncal obesity, wasting of her distal musculature and moon facies. In addition she complains of abnormal stretch marks that surround her abdomen. The physician suspects pituitary adenoma. Which of the following high-dose dexamethasone suppression test findings and baseline ACTH findings would support his view?

Cortisol suppression, high baseline ACTH

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B

A 64-year-old man presents to his physician 6 months after experiencing a myocardial infarction. The patient currently denies any symptoms and is only in for a check up. The patient's past medical history is notable for diabetes (type II), obesity, hypertension and cyclothymia. His current medications are hydrocholorthiazide, metoprolol, metformin, insulin, fluoxetine, and fish oil. On physical exam you note a calm elderly man who is moderately obese and in no current distress. The patient's cardiovascular exam is notable for a S4 heart sound. The patients lab work is below. Serum: Na+: 140 mEq/L Cl-: 100 mEq/L K+: 4.4 mEq/L HCO3-: 23 mEq/L BUN: 20 mg/dL Glucose: 120 mg/dL Creatinine: 1.6 mg/dL Ca2+: 10.1 mg/dL AST: 11 U/L ALT: 9 U/L Cholesterol: 190 mg/dL Triglycerides: 150 mg/dL High density lipoprotein associated cholesterol: 11 mg/dL Low density lipoprotein associated cholesterol: 149 mg/dL The physician updates the patient's medication regimen after this visit. The patient returns 2 weeks later and presents his blood glucose diary to you demonstrating a mean blood glucose of 167 mg/dL. He is also complaining of flushing that occurs occasionally but otherwise is doing well. Which of the following is most likely to alleviate this patient's current symptom?

Irreversible inactivation of cyclooxygenase

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D

A 32-year-old woman comes to the physician with increasing jaundice and fatigue for the past week. She has no history of a serious illness. She takes no medications and denies use of recreational drugs. She does not drink alcohol. Her vital signs are within normal limits. Her body mass index is 21 kg/m2. On physical examination, she has icteric sclera. Otherwise, her heart and lung sounds are within normal limits. Hemoglobin 15 g/dL Leukocyte count 6,000/mm3 with a normal differential Serum bilirubin Total 6.5 mg/dL Direct 0.9 mg/dL Alkaline phosphatase 70 U/L Aspartate aminotransferase (AST, GOT) 430 U/L Alanine aminotransferase (ALT, GPT) 560 U/L γ-Glutamyltransferase (GGT) 43 U/L (N=5-50 U/L) Hepatitis A antibody Negative Hepatitis B surface antigen Negative Hepatitis C antibody Negative Rheumatoid factor 80 IU/mL (N=0-20 IU/mL) Antinuclear antibody (ANA) titer is 1:1280. Polyclonal immunoglobulin gamma is 5 g/dL. Which of the following antibodies is most likely to be positive in this patient?

Anti-smooth muscle

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E

A 22-year-old female presents at 24 weeks gestation with a chief complaint of burning upon urination. On physical exam, you note a gravid uterus that extends above the umbilicus. A urine analysis and culture is sent demonstrating over 100,000 colony forming units of E. coli. Of note this patient had a similar UTI 7 weeks ago that was resolved with appropriate medication. Which of the following is the most appropriate management of this patient?

Nitrofurantoin and continue with nitrofurantoin prophylaxis for the rest of the pregnancy

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D

n 18-month-old toddler is brought to the pediatrician by her mother for cough. The mother reports that her daughter has had a productive-sounding cough and runny nose for the past 2 days. She has also noticed that her daughter feels warm. On chart review, this is the 4th time this patient is presenting for similar concerns; the 3 previous diagnoses were otitis media (2 episodes) and bacterial sinusitis (1 episode). Her temperature is 38.3°C (101.0°F). Physical examination is notable for cough and purulent sputum from both nares, although her lungs are clear to auscultation. Sputum gram stain shows gram-positive diplococci. Serum immunoglobulin studies show normal levels of IgM and decreased levels of IgG and IgA. Which of the following is the most likely underlying diagnosis in this patient?

Hyper-IgM syndrome

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C

A 56-year old man presents to his primary care physician complaining of a dark spot on his left thigh. He says that he first noticed the spot about 3 years ago when he went to the beach with his family; however, at the time it was very small and he didn't think that it was worth mentioning. Since then, it has been growing slowly and he is now concerned about its size. He says that he does not have any other symptoms associated with the lesion. Physical exam reveals an asymmetric 2.5 centimeter plaque with irregular borders and a varying pattern of brown coloration. The lesion is studied and found to have a mutation in a gene that inhibits cyclin function. Which of the following is most likely true of this gene?

Both copies of the gene encoding the target are non-functional in tumors

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A

A 35-year-old African American male is admitted to the hospital following a recent diagnosis of systemic histoplasmosis and subsequently treated with an intravenous anti-fungal agent. During the course of his hospital stay, he complains of headaches. Work-up reveals hypotension, anemia, and elevated BUN and creatinine. His medication is known to cause these side-effects through its binding of cell membrane ergosterol. With which anti-fungal is he most likely being treated?

Amphotericin B

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C

An otherwise healthy 13-year-old boy is brought to the physician because of asthma attacks that have been increasing in frequency and severity over the past 4 weeks. He was first diagnosed with asthma 6 months ago. Current medications include high-dose inhaled fluticasone and salmeterol daily, with additional albuterol as needed. He has required several courses of oral corticosteroids. A medication is added to his therapy regimen that results in downregulation of the high-affinity IgE receptor (FcεRI) on mast cells and basophils. Which of the following drugs was most likely added to the patient's medication regimen?

Omalizumab

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B

A 26-year-old man is brought to the emergency department because of abdominal pain, dizziness, shortness of breath, and swelling and pruritus of the lips, tongue, and throat for 1 hour. The symptoms began minutes after he started eating a lobster dinner. It is determined that his symptoms are due to surface crosslinking of IgE. This immunologic event most likely caused the release of which of the following?

Tryptase

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A

A 62-year-old man comes to the physician because of a skin lesion on his nose. The patient has had the lesion for 11 months and it has increased in size over the past few months. He is a farmer and lives together with his wife. His mother died of metastatic melanoma at the age of 67 years. The patient has smoked a pack of cigarettes daily for the past 30 years and drinks 1–2 glasses of whiskey on weekends. His temperature is 36.8°C (98.2°F), pulse is 75/min, and blood pressure is 140/78 mm Hg. Examination of the skin shows a nontender lesion at the right root of the nose. An image of the lesion is shown. Which of the following is the most likely diagnosis in this patient?

Basal cell carcinoma

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C

A 49-year-old man presents to a physician with the complaint of pain in the thigh after walking. He says that he is an office clerk with a sedentary lifestyle and usually drives to his office. On 2 occasions last month he had to walk to his office, which is less than a quarter of a mile from his home. On both occasions, soon after walking, he experienced pain in the right thigh which subsided spontaneously within a few minutes. His past medical history is negative for hypertension, hypercholesterolemia, or ischemic heart disease. He is a non-smoker and non-alcoholic. His father has ischemic heart disease. His physical examination is within normal limits, and the peripheral pulses are palpable in all extremities. His detailed diagnostic evaluation, including magnetic resonance angiogram (MRA) and exercise treadmill ankle-brachial index (ABI) testing, suggests a diagnosis of peripheral vascular disease due to atherosclerosis of the right iliac artery. Which of the following is the best initial treatment option?

Exercise therapy

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A

A 38-year-old woman comes to the physician because of a 1-month history of palpitations. She does not smoke or drink alcohol. Her pulse is 136/min and irregularly irregular. An ECG shows irregularly spaced QRS complexes with no distinct P waves. Treatment is started with a drug that slows atrioventricular node conduction velocity and prevents voltage-dependent calcium entry into myocytes. The patient is at greatest risk for which of the following adverse effects?

Gingival hyperplasia

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E

A 45-year-old male presents to the hospital complaining of frequent headaches and a decreased libido. During the physical exam, the patient also states that he has recently been experiencing vision problems. The patient is suffering from what type of adenoma?

Lactotroph

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B

A 62-year-old man presents for evaluation of an adrenal nodule, which was accidentally discovered while performing a computerized tomography (CT) scan of the abdomen for recurrent abdominal pain. The CT was negative except for a 3 cm low-density, well-circumscribed nodule in the left adrenal gland. He reports weight gain of 12 kg (26.4 lb) over the past 3 years. He has type 2 diabetes mellitus and hypertension, which have been difficult to control with medications. Which of the following is the best initial test for this patient?

1 mg overnight dexamethasone suppression test

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C

A 48-year-old woman presents to an urgent care clinic with the complaints of bloody diarrhea, mid-abdominal discomfort, and cramping for 3 days. She also has nausea, vomiting, and fever. She reports that she had eaten raw oysters at a local seafood restaurant almost 3 days ago, but she denies any other potentially infectious exposures. Her temperature is 37.5°C (99.6°F), respiratory rate is 15/min, pulse is 67/min, and blood pressure is 102/68 mm Hg. Physical examination is non-contributory. What is the most likely diagnosis?

Vibrio parahaemolyticus infection

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E

The parents of a newly adopted 5-year-old child brought him to the pediatrician after he started to have bouts of diarrhea and bloating. His symptoms are worse after consuming dairy products and ice cream. The immunization history is up to date. His height and weight are in the 60th and 70th percentiles, respectively. His physical examination is normal. The pediatrician orders some lab tests because she believes there is a biochemical disorder. What is the first-line therapy for the most likely condition?

Diet modification

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D

A 19-year-old man presents to the emergency room after a suicidal gesture following a fight with his new girlfriend. He tearfully tells you that she is “definitely the one," unlike his numerous previous girlfriends, who were "all mean and selfish” and with whom he frequently fought. During this fight, his current girlfriend suggested that they spend time apart, so he opened a window and threatened to jump unless she promised to never leave him. You gather that his other relationships have ended in similar ways. He endorses impulsive behaviors and describes his moods as “intense” and rapidly changing in response to people around him. He often feels “depressed” for one day and then elated the next. You notice several superficial cuts and scars on the patient’s arms and wrists, and he admits to cutting his wrists in order to “feel something other than my emptiness.” Which of the following is the most likely diagnosis for this patient?

Borderline personality disorder

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C

Two weeks after hospitalization for acute psychosis, a 27-year-old woman with a history of paranoid schizophrenia comes to the physician because of difficulty walking and shaking movements of her hands. Current medications include fluphenazine, which was started during her recent hospitalization. Examination shows a shuffling gait, rigidity in the upper extremities, and a low-amplitude tremor of her hands that improves with activity. Mental status examination shows no abnormalities. Treatment with a drug with which of the following mechanisms of action is most likely to provide relief for this patient's current symptoms?

Muscarinic antagonist

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E

A 22-year-old man is brought to the emergency department 30 minutes after being involved in a high-speed motor vehicle collision in which he was the unrestrained driver. After extrication, he had severe neck pain and was unable to move his arms and legs. On arrival, he is lethargic and cannot provide a history. Hospital records show that eight months ago, he underwent an open reduction and internal fixation of the right humerus. His neck is immobilized in a cervical collar. Intravenous fluids are being administered. His pulse is 64/min, respirations are 8/min and irregular, and blood pressure is 104/64 mm Hg. Examination shows multiple bruises over the chest, abdomen, and extremities. There is flaccid paralysis and absent reflexes in all extremities. Sensory examination shows decreased sensation below the shoulders. Cardiopulmonary examination shows no abnormalities. The abdomen is soft. There is swelling of the right ankle and right knee. Squeezing of the glans penis does not produce anal sphincter contraction. A focused assessment with sonography for trauma shows no abnormalities. He is intubated and mechanically ventilated. Which of the following is the most appropriate next step in management?

Placement of Foley catheter

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A

A 65-year-old man is brought to the emergency department because of a 1-day history of fever and disorientation. His wife reports that he had abdominal pain and diarrhea the previous day. He drinks 60 oz of alcohol weekly. His pulse is 110/min and blood pressure is 96/58 mm Hg. Examination shows jaundice, palmar erythema, spider nevi on his chest, dilated veins on the anterior abdominal wall, and 2+ edema of the lower extremities. The abdomen is soft and diffusely tender; there is shifting dullness to percussion. His albumin is 1.4 g/dL, bilirubin is 5 mg/dL, and prothrombin time is 31 seconds (INR = 3.3). Hepatitis serology is negative. A CT scan of the abdomen is shown. Which of the following processes is the most likely explanation for these findings?

Fibrous bands surrounding regenerating hepatocytes

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C

A 10-year-old boy is brought to the physician by his parents because they are concerned about his “strange behavior”. The boy was born at 39 weeks gestation via spontaneous vaginal delivery. He is up to date on all vaccines and is meeting all developmental milestones. The parents state that he has always been a solitary child without many friends, but that recently, he has been having behavioral problems that seem to be unprovoked and are occurring more frequently. The child will throw a tantrum for no reason and does not respond to punishment or reward. He also has a 'strange obsession' with collecting rocks that he finds on his way to and from school, so much so that his room is filled with rocks. His teachers say he “daydreams a lot” and is very good at art, being able to recreate his favorite cartoon characters in great detail. On assessment, the patient does not make eye contact with the physician but talks incessantly about his rock collection. The child’s grammar and vocabulary seem normal, but his speech is slightly labored. Which of the following is the most likely diagnosis?

Autism spectrum disorder, level 1

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A

A pathologist receives a skin biopsy specimen from a patient who is suspected to have developed graft-versus-host disease (GVHD) following allogeneic stem-cell transplantation. The treating physician informs the pathologist that he is specifically concerned about the diagnosis as the patient developed skin lesions on the 90th-day post-transplantation and therefore, by definition, it should be considered a case of acute GVHD. However, the lesions clinically appear like those of chronic GVHD. The pathologist examines the slide under the microscope and confirms the diagnosis of chronic GVHD. Which of the following findings on skin biopsy is most likely to have helped the pathologist to confirm the diagnosis?

Hypergranulosis

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C

A 21-year-old woman is brought to the emergency department following a motor vehicle collision. She has significant pain and weakness in her right arm and hand. Physical examination shows multiple ecchymoses and tenderness in the right upper extremity. She is able to make a fist, but there is marked decrease in grip strength. An x-ray of the right upper extremity shows a midshaft humerus fracture. Which of the following structures is most likely injured?

Radial nerve

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B

A 44-year-old woman is brought to the emergency department because of confusion and agitation. She was brought by police after she was found walking along a highway. The patient's brother comes to join her soon after her arrival. He says she has peptic ulcer disease and hypertension. He thinks she drinks around half a bottle of vodka daily. Her current medications include omeprazole and hydrochlorothiazide, although the brother is unsure if she takes them regularly. Her temperature is 37.1°C (98.7°F), pulse is 90/min, respirations are 16/min, and blood pressure is 135/90 mm Hg. On mental status examination, she is confused and not oriented to person, place, or time. Neurologic examination shows horizontal nystagmus. Her gait is wide-based with small steps. Her hemoglobin concentration is 9 g/dL. Her serum homocysteine concentration is elevated and her methylmalonic acid concentration is within the reference range. A peripheral blood smear shows hypersegmented neutrophils. Which of the following is the most likely cause of this patient's anemia?

Folate deficiency

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A

A 12-year-old boy is brought to his primary care physician because he has been tripping and falling frequently over the past 2 months. He says that he feels like he loses his balance easily and finds it difficult to walk in tight spaces such as his school hallways. Furthermore, he says that he has been experiencing insomnia over the same time period. His past medical history is significant for some mild allergies, but otherwise he has been healthy. Physical exam reveals that his eyes are fixed downwards with nystagmus bilaterally. Which of the following structures is most likely affected by this patient's condition?

Pineal gland

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C

A 60-year-old man with a 1-year history of recurrent aspiration pneumonia is brought to the emergency department by his daughter after being found unconscious and gasping for air in his bed. Despite resuscitative efforts, the patient dies. Autopsy of the patient shows degeneration of the corticospinal tracts and anterior horn cells of the upper cervical cord. There is asymmetrical atrophy of the limb muscles, the diaphragm, and the intercostal muscles. Which of the following drugs would have most likely slowed the progression of this patient's condition?

Riluzole

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E

A 42-year-old man presents to the emergency room complaining of a painful, swollen tongue that is making it hard to talk and swallow. The patient denies trauma, trouble breathing, and skin rashes. The patient has no known allergies and a minimal past medical history, except for newly diagnosed hypertension for which he was just started on a new medication. The patient is afebrile, the blood pressure is 145/110 mm Hg, the heart rate is 88/min, and the O2 saturation is 97% on room air. What is the mechanism of this reaction?

Decreased bradykinin degradation

step1

D

A 56-year-old man comes to the emergency department because of chest pain. The pain occurs intermittently in 5-minute episodes. It is not conclusively brought on by exertion and sometimes occurs at rest. He has a history of hyperlipidemia and takes a high-dose statin daily. His father died of lung cancer at the age of 67 years and his mother has type 2 diabetes. He smokes a pack of cigarettes daily and does not drink alcohol. His temperature is 37°C (98.8°F), pulse is 88/min, and blood pressure is 124/72 mm Hg. Cardiac examination shows no abnormalities. He has no chest wall tenderness and pain is not reproduced with palpation. While waiting for laboratory results, he has another episode of chest pain. During this event, an ECG shows ST elevations in leads II, III, and aVF that are > 1 mm. Thirty minutes later, a new ECG shows no abnormalities. Troponin I level is 0.008 ng/mL (normal value < 0.01 ng/mL). Cardiac angiography is performed and shows a 30% blockage of the proximal right circumflex artery and 10% blockage in the distal left circumflex artery. This patient's condition is most closely associated with which of the following?

Raynaud phenomenon "

step2&3

E

A 5-year-old boy is referred to an immunologist because of episodes of recurrent infections. He complains of ear pain, nasal discharge, congestion, and headache. His medical history is significant for neonatal sepsis, recurrent bronchitis, and otitis media. The boy also had pneumocystis pneumonia when he was 11 months old. His mother reports that she had a younger brother who had multiple serious infections and died when he was 4 years old because of otogenic sepsis. Her grandfather frequently developed pneumonia and had multiple episodes of diarrhea. The patient is in the 10th percentile for height and 40th percentile for weight. The vital signs include: blood pressure 90/60 mm Hg, heart rate 111/min, respiratory rate 26/min, and temperature 38.3°C (100.9°F). Physical examination reveals a red, swollen, and bulging eardrum and enlarged retroauricular lymph nodes. Meningeal signs are negative and the physician suspects the presence of a primary immunodeficiency. After a thorough laboratory investigation, the patient is found to be CD40L deficient. Despite this deficiency, which of the following chains would still be expressed normally in this patient’s B lymphocytes?

μ and δ heavy chains

step1

A

A 65-year-old man presents to the emergency department for a loss of vision. He was outside gardening when he suddenly lost vision in his right eye. He then immediately called emergency medical services, but by the time they arrived, the episode had resolved. Currently, he states that he feels fine. The patient has a past medical history of diabetes and hypertension. His current medications include lisinopril, atorvastatin, metformin, and insulin. His temperature is 99.5°F (37.5°C), blood pressure is 140/95 mmHg, pulse is 90/min, respirations are 12/min, and oxygen saturation is 98% on room air. Cardiac exam is notable for a systolic murmur along the right sternal border that radiates to the carotids. Pulmonary exam reveals mild bibasilar crackles. Neurological exam reveals cranial nerves II-XII as grossly intact with 5/5 strength and normal sensation in the upper and lower extremities. The patient has a negative Romberg's maneuver, and his gait is stable. A CT scan of the head demonstrates mild cerebral atrophy but no other findings. Which of the following is the next best step in management?

Ultrasound of the neck

step2&3

D

A 54-year-old woman comes to the physician because of a 3-month history of upper midthoracic back pain. The pain is severe, dull in quality, and worse during the night. Ten months ago, she underwent a modified radical mastectomy for invasive ductal carcinoma of the right breast. Physical examination shows normal muscle strength. Deep tendon reflexes are 2+ in all extremities. Examination of the back shows tenderness over the thoracic spinous processes. An x-ray of the thoracic spine shows vertebral osteolytic lesions at the levels of T4 and T5. The patient's thoracic lesions are most likely a result of metastatic spread via which of the following structures?

Azygos vein

step1

B

A 52-year-old woman comes to the emergency department because of a 3-hour history of right flank pain and nausea. Her only medication is a multivitamin. Her vital signs are within normal limits. Physical examination shows tenderness in the right costovertebral angle. Urinalysis shows a pH of 5.1, 50–60 RBC/hpf, and dumbbell-shaped crystals. Which of the following best describes the composition of the crystals seen on urinalysis?

Calcium oxalate

step1

B

A 24-year-old woman presents to the emergency department when she was found yelling and screaming outside a bowling alley. The patient was found smoking marijuana and eating pizza while stating “if I'm going to die I'm going to die happy.” She was brought in by police and has been compliant since her arrival. Upon questioning, the patient states that she has had technology implanted in her for quite a while now, and she knows she will die soon. Any attempts to obtain further history are not helpful. The patient’s parents are contacted who provide additional history. They state that the patient recently started college 3 months ago. Two months ago, the patient began complaining about “technology” and seemed at times to converse with inanimate objects. On physical exam, you note a healthy young woman whose neurological exam is within normal limits. The patient is fixated on her original story and does not offer any information about her past medical history or current medications. Which of the following is the most likely diagnosis?

Schizophreniform disorder

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E

A 42-year-old gentleman presents to his primary care physician with complaints of persistent headaches and general weakness. He was recently diagnosed with severe hypertension that has been refractory to anti-hypertensive medications. Based on clinical suspicion, a basic metabolic panel is obtained which demonstrates a sodium level of 153 mg/dl and a potassium level of 2.9 mg/dl. The hormone that is the most likely cause of this patient's presentation is normally secreted by which region of the adrenal gland?

Zona Glomerulosa

step1

B

A 52-year-old woman with HIV infection is brought to the emergency department 20 minutes after she had a generalized tonic-clonic seizure. She appears lethargic and confused. Laboratory studies show a CD4+ count of 89 cells/μL (N > 500). A CT scan of the head with contrast shows multiple ring-enhancing lesions in the basal ganglia and subcortical white matter. An India ink preparation of cerebrospinal fluid is negative. Which of the following is the most likely diagnosis?

Cerebral toxoplasmosis

step1

E

A scientist is studying the process of thymus-dependent B cell activation in humans. He observes that, after bacterial infections, the germinal centers of secondary lymphoid organs become highly metabolically active. After subsequent reinfection with the same pathogen, the organism is able to produce immunoglobulins at a much faster pace. Which of the following processes is likely taking place in the germinal centers at the beginning of an infection?

Affinity maturation

step1

E

A 43-year-old woman presents to the physician because of a persistent rash on her right nipple for 1 month. The rash has persisted despite topical medication. She has no personal or family history of any serious illnesses. Other medications include oral contraceptive pills. She is single and has never had any children. Vital signs are within normal limits. An image of the right breast and nipple is shown. Palpation of the right breast shows a 2 x 2 cm under the areola. Lymphadenopathy is palpated in the right axilla. The remainder of the physical examination shows no abnormalities. A mammogram shows subareolar microcalcifications. Which of the following types of breast cancer is most likely to be found in this patient?

Invasive ductal carcinoma

step2&3

B

A 65-year-old woman comes to the physician because of a 2-month history of persistent pain in her right shoulder. The pain is localized to the top of the shoulder and is worse with movement. She has stiffness in the right shoulder that is worse in the morning and usually lasts 20 minutes. The patient reports that she is unable to brush her hair and has stopped going to her regular tennis lessons because of the pain. She does not recall any fall or trauma. When her right arm is passively abducted in an arc, there is pain between 60 and 120 degrees of abduction. When asked to lower the right arm slowly from 90 degrees of abduction, she is unable to hold her arm up and it drops to her side. Passive range of motion is normal. Injection of 5 mL of 1% lidocaine into the right subacromial space does not relieve the pain or improve active range of motion of the right arm. Which of the following is the most likely diagnosis?

Rotator cuff tear

step2&3

B

A 66-year-old male presents to the outpatient cardiology clinic for evaluation of suspected primary hypertension. His blood pressure is elevated to 169/96 mm Hg, and his heart rate is 85/min. Physical examination reveals an overweight male with regular heart and lung sounds. Following repeated elevated blood pressure measurements, the diagnosis is made and the patient is started on hydrochlorothiazide. Of the following options, which is a side effect that one could experience from thiazide-like diuretics?

Hyperuricemia

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A

A group of scientists studying the properties of muscle cells in vitro decide to conduct an experiment to observe their distinguishing properties. 3 types of muscle cells isolated from human tissues are labeled as X, Y, and Z and placed in physiological solutions alongside controls X’, Y’ and Z’. Antibodies against the sarcoplasmic Ca2+ ATPase are added to the solutions containing the experimental group and their cytosolic calcium concentration is compared with their corresponding controls 5 minutes after depolarization. Muscle type X is seen to have the highest cytosolic calcium concentration among the experimental and control groups 5 minutes after depolarization. Muscle types Y and Z, on the other hand, are both observed to have lower, equal cytosolic calcium concentrations but higher than their corresponding controls. To distinguish between the 2 cell types, the scientists tag both cells with a compound capable of fluorescing titin and observes a luminescent pattern in muscle type Y under microscopy. Which of the following set of muscle cell types best describes X, Y, and Z respectively?

Skeletal muscle, cardiac muscle, smooth muscle

step1

C

A 3-year-old girl presents with her mother for a well-child checkup. Recent laboratory data has demonstrated a persistent normocytic anemia. Her mother denies any previous history of blood clots in her past, but she says that her mother has also had to be treated for pulmonary embolism in the recent past, and her brother has had to deal with anemia his entire life. The patient’s past medical history is noncontributory other than frequent middle ear infections. The vital signs upon arrival include: temperature, 36.7°C (98.0°F); blood pressure, 106/74 mm Hg; heart rate, 111/min and regular; and respiratory rate, 17/min. On physical examination, her pulses are bounding and fingernails are pale, but breath sounds remain clear. Oxygen saturation was initially 91% on room air and electrocardiogram (ECG) shows sinus tachycardia. The patient’s primary care physician orders a peripheral blood smear to further evaluate this finding, and preliminary results show a hemolytic anemia. Which of the following pathophysiologic mechanisms best describes sickle cell disease?

A recessive beta-globin mutation causing morphological changes to the RBC

step2&3

C

A 62-year-old woman presents to the primary care physician with complaints of urinary leakage over the last 2 months. History reveals that the leakage occurred when she sneezed, laughed, or coughed. Her menopause occurred 11 years ago and she is a mother of 3 children. Vital signs include blood pressure 120/80 mm Hg, heart rate 84/min, respiratory rate 18/min, and temperature 36.6°C (98.0°F). Physical examination is unremarkable. Urinalysis reveals: Color Yellow Clarity/turbidity Clear pH 5.5 Specific gravity 1.015 Nitrites Negative Leukocyte esterase Negative Which of the following is the best initial management for this patient?

Kegel exercises

step2&3

B

A 15-year-old boy with Down syndrome is admitted to the hospital because of a 2-week history of pallor, easy bruising, and progressive fatigue. He has a history of acute lymphoblastic leukemia that has been in remission for 2 years. Examination shows cervical and axillary lymphadenopathy. Bone marrow biopsy predominantly shows immature cells that stain positive for terminal deoxynucleotidyl transferase. A diagnosis of relapsed acute lymphoblastic leukemia is made. Treatment with a combination chemotherapeutic regimen including teniposide is initiated. The effect of this drug is best explained by which of the following mechanisms of action?

Increase in double-stranded DNA breaks

step1

C

A 68-year-old man, accompanied by his wife, presents to his physician with cognitive decline and hallucinations. The patient’s wife tells that his cognitive impairment progressed gradually over the past 6 years, and first began with problems counting and attention. The hallucinations began approximately a year ago. The patient describes them as realistic and non-frightening; most often, he sees his cat accompanying him everywhere he goes. The patient’s wife also notes frequent episodes of staring spells in her husband and prolonged daytime napping. The blood pressure is 130/80 mm Hg with the orthostatic change to 110/60 mm Hg, heart rate is 75/min, respiratory rate is 13/min, and the temperature is 36.6°C (97.8°F). The patient is alert and responsive, but he is disoriented to time and place. He is pale and hypomimic. The cardiac, lung, and abdominal examinations are within normal limits for the patient’s age. The neurological examination is significant for a bilateral symmetrical cogwheel rigidity in the upper extremities. What would you most likely see on additional radiological investigations?

Decreased perfusion and dopaminergic activity in occipital lobes on PET

step2&3

A

A 14-year-old Somalian boy is brought to the emergency department by his mother because of a painful penile erection since he woke up 3 hours ago. His family recently emigrated to the United States from a refugee camp, and his past medical history is unknown. He has never had a health check up prior to this visit. On further questioning, his mother reports that the child is often fatigued and sick, and has episodes of joint pain. Examination shows ejection systolic murmurs heard over the precordium. Examination of the genitalia shows an engorged, tumescent penis. The remainder of the examination shows no abnormalities. Which of the following is the most likely underlying cause?

Sickle cell disease

step2&3

A

A 48-year-old female presents to your office with a 1-year history of dry eyes and difficulty swallowing. She complains of blinking frequently and of eye strain while using her computer at work. She also reports stiffness in her knees and lower back. Past medical history is unremarkable and she does not take medications. She denies cigarette or alcohol use. Family history is notable for Hashimoto's thyroiditis in her mother. Physical exam shows dry oral mucosa and enlargement of the parotid glands. Which of the following serologies is likely to be positive in this patient?

Anti-SS-A

step1

A

A 13-year-old boy is brought to the emergency room by his mother for a generalized tonic-clonic seizure that occurred while attending a laser light show. The patient’s mother reports that he has been otherwise healthy but states, “he often daydreams”. Over the past several months, he has reported recurrent episodes of jerky movements involving his fingers and arms. These episodes usually occurred shortly after waking up in the morning. He has not lost consciousness during these episodes. Which of the following is the most appropriate treatment for this patient's condition?

Valproate

step2&3

E

An 81-year-old woman presents to her physician complaining of occasional right-sided weakness in her arm and leg. She reports 3 such episodes over the last 6 months, each lasting only 1 hour and not significantly affecting her daily functioning. The patient denies numbness and tingling, pain, weakness in her left side, and changes in her speech. She has a past medical history of hypertension and coronary artery disease with stable angina, and her medications include 81 mg aspirin, 20 mg lisinopril, 5 mg amlodipine, and 20 mg atorvastatin daily. The patient reports a 40-pack-year smoking history and occasional alcohol intake. At this visit, her temperature is 98.5°F (36.9°C), blood pressure is 142/87 mmHg, pulse is 70/min, and respirations are 14/min. She has a grade II systolic ejection murmur best heard at the right upper sternal border, and there is a carotid bruit on the left side. Her lungs are clear. Neurologic exam reveals intact cranial nerve function, 1+ deep tendon reflexes in bilateral patellae and biceps, as well as 5/5 strength and intact pinprick sensation in all extremities. Carotid ultrasound is performed and identifies 52% stenosis on the right side and 88% on the left. Which of the following is the best next step in management?

Perform carotid endarterectomy on left side only

step2&3

E

A 49-year-old woman comes to the office complaining of 2 weeks of urinary incontinence. She says she first noticed some light, urinary dribbling that would increase with sneezing or coughing. This dribble soon worsened, soaking through a pad every 3 hours. She denies any fevers, chills, abdominal pain, hematuria, dysuria, abnormal vaginal discharge, or increased urinary frequency. The patient had a bilateral tubal ligation 3 weeks ago. Her last menstrual period was 2 weeks ago. Her menses are regular and last 5 days. She has had 3 pregnancies that each resulted in uncomplicated, term vaginal deliveries. Her last pregnancy was 2 years ago. The patient has hypothyroidism and takes daily levothyroxine. She denies tobacco, alcohol, or illicit drug use. She has no history of sexually transmitted diseases. She is sexually active with her husband of 25 years. Her BMI is 26 kg/m^2. On physical examination, the abdomen is soft, nondistended, and nontender without palpable masses or hepatosplenomegaly. Rectal tone is normal. The uterus is anteverted, mobile, and nontender. There are no adnexal masses. Urine is seen pooling in the vaginal vault. Urinalysis is unremarkable. Which of the following is next best step in diagnosis?

Methylene blue instillation into the bladder

step2&3

B

A biology graduate student is performing an experiment in the immunology laboratory. He is researching the recombination activation genes RAG1 and RAG2 in order to verify the function of these genes. He then decides to carry out the experiment on knock-out mice so that these genes will be turned off. Which of the following changes should he be expecting to see?

Total lack of B and T cells

step1

B

Please refer to the summary above to answer this question Which of the following is most appropriate to confirm the diagnosis in this patient?" "Patient information Age: 62 years Gender: F, self-identified Ethnicity: unspecified Site of care: office History Reason for Visit/Chief Concern: “My cough is getting worse.” History of Present Illness: 12-month history of episodic cough and dyspnea; episodes last multiple weeks and have improved with antibiotics cough is usually productive of large amounts of yellow sputum; in the past 2 days, it has been productive of cupfuls of yellow-green sputum has occasionally noticed streaks of blood in the sputum has not had fever, chills, or chest pain Past Medical History: type 2 diabetes mellitus kidney transplantation 3 years ago for diabetic nephropathy hyperlipidemia osteoporosis Social History: does not smoke, drink alcohol, or use illicit drugs Medications: mycophenolate mofetil, prednisone, metformin, atorvastatin, alendronate Allergies: no known drug allergies Physical Examination Temp Pulse Resp. BP O2 Sat Ht Wt BMI 37.6°C (99.7°F) 80/min 18/min 138/86 mm Hg 97% 165 cm (5 ft 5 in) 58 kg (128 lb) 21 kg/m2 Appearance: mildly uncomfortable, sitting on the examination table Neck: no jugular venous distention Pulmonary: cough productive of yellow-green sputum; mildly diminished lung sounds over all lung fields; bilateral expiratory wheezes, rhonchi, and crackles are heard Cardiac: normal S1 and S2; no murmurs, rubs, or gallops Abdominal: soft; nontender; a well-healed left lower abdominal scar is present at the site of kidney transplantation; normal bowel sounds Extremities: digital clubbing; no joint erythema, edema, or warmth; dorsalis pedis and radial pulses intact Skin: no rashes Neurologic: alert and oriented; cranial nerves grossly intact; no focal neurologic deficits"

High-resolution CT scan of the chest

step2&3

D

A 5-year-old girl is brought to the physician by her parents because of difficulty at school. She does not listen to her teachers or complete assignments as requested. She does not play or interact with her peers. The girl also ignores her parents. Throughout the visit, she draws circles repeatedly and avoids eye contact. Physical and neurological examination shows no abnormalities. Which of the following is the most likely diagnosis?

Autism spectrum disorder

step1

C

A 74-year-old Hispanic man comes to the physician because of a three-week history of dizziness upon standing and a brief loss of consciousness one hour ago. The patient suddenly collapsed on his way to the bathroom after waking up in the morning. He did not sustain any injuries from his collapse. He has a history of gastroesophageal reflux disease, benign prostatic hyperplasia, and gout. The patient's mother died of a grand mal seizure at the age of 53 years. He has smoked one pack of cigarettes daily for 55 years. He drinks three beers and two glasses of whiskey daily. Current medications include ranitidine, dutasteride, tamsulosin, and allopurinol. He is 166 cm (5 ft 5 in) tall and weighs 62 kg (137 lb); BMI is 22.5 kg/m2. He appears pale. Temperature is 36.7°C (98.0°F), pulse is 83/min, and blood pressure is 125/80 mm Hg supine and 100/70 mm Hg one minute after standing with no change in pulse rate. Physical examination shows conjunctival pallor. A plopping sound is heard on auscultation, immediately followed by a low-pitched, rumbling mid-diastolic murmur heard best at the apex. The remainder of the examination shows no abnormalities. An ECG shows regular sinus rhythm. Which of the following is the most likely diagnosis?

Cardiac myxoma

step2&3

A

A 41-year-old man presents to his primary care provider complaining of a blistering skin rash. He was out in the sun with his family at a baseball game several days ago. Later that evening he developed a severe blistering rash on his forearms, back of his neck, and legs. He denies fevers, chills, malaise, abdominal pain, or chest pain. He denies dysuria or a change in his bowel patterns but does report that his urine has occasionally appeared brown over the past few months. His family history is notable for hemochromatosis in his father. He does not smoke or drink alcohol. On examination, he has small ruptured blisters diffusely across his forearms, back of his neck, and lower legs. This patient most likely has a condition caused by a defect in an enzyme that metabolizes which of the following compounds?

Uroporphyrinogen

step1

E

A 45-year-old male presents to your office with complaints of chronic insomnia. After reviewing his medical history, you decide to prescribe zolpidem. Which of the following is a valid reason to choose zolpidem over a benzodiazepine?

Zolpidem has a lower risk of tolerance and dependence

step1

C

You are conducting a systematic review on the effect of a new sulfonylurea for the treatment of type II diabetes. For your systematic review you would like to include 95% confidence intervals for the mean of blood glucose levels in the treatment groups. What further information is necessary to abstract from each of the original papers in order to calculate a 95% confidence interval for each study?

Standard deviation, mean, sample size

step1

D

A 35-year-old woman comes to the physician for the evaluation of fatigue and dizziness for the past 2 months. During this period, she has also had mild upper abdominal pain that is not related to food intake. She has no personal or family history of serious illness. She immigrated to the United States from Italy 10 years ago. Menses occur at regular 28-day intervals with moderate flow. She does not smoke or drink alcohol. She takes no medications. Her vital signs are within normal limits. The spleen is palpated 2 cm below the left costal margin. There is no scleral icterus. Neurologic examination shows no abnormalities. Laboratory studies show: Hemoglobin 11.2 g/dL Mean corpuscular volume 62 μm3 Leukocyte count 7,000/mm3 Platelet count 260,000/mm3 A peripheral blood smear shows target cells. The patient is started on iron supplementation. Three weeks later, her laboratory studies are unchanged. Which of the following is the most likely underlying cause of this patient’s condition?"

Mutation in the beta-globin gene

step2&3

C

A researcher faces the task of calculating the mean height of male students in an undergraduate class containing a total of 2,000 male students and 1,750 female students. The mean height of a sample of male students is computed as 176 cm (69.3 in), with a standard deviation of 7 cm (2.8 in). The researcher now tries to calculate the confidence interval for the mean height of the male students in the undergraduate class. Which additional data will be needed for this calculation?

Total sample size of the study

step1

E

A 38-year-old man presents to a fertility specialist. He is concerned that he is infertile. His wife had two children from a previous marriage and has regular menses. They have been married three years and have been trying to conceive for the past two. His vitals are normal. Physical exam reveals bilateral gynecomastia, elongated limbs, and small testicles. Levels of plasma gonadotropins are elevated. Which of the following is likely to be also elevated in this patient?

Aromatase

step1

C

A 25-year-old man comes to the physician because of left-sided knee pain for 2 weeks. The pain started while playing basketball after suddenly hearing a popping sound. He has been unable to run since this incident. He has asthma, allergic rhinitis, and had a progressive bilateral sensorineural hearing impairment at birth treated with cochlear implants. His only medication is a salbutamol inhaler. The patient appears healthy and well-nourished. His temperature is 37°C (98.6°F), pulse is 67/min, and blood pressure is 120/80 mm Hg. Examination of the left knee shows medial joint line tenderness. Total knee extension is not possible and a clicking sound is heard when the knee is extended. An x-ray of the left knee shows no abnormalities. Which of the following is the most appropriate next step in the management of this patient?

Arthroscopy of the left knee

step2&3

E

A 34-year-old Caucasian female presents with truncal obesity, a rounded "moon face", and a "buffalo hump". Serum analysis shows hyperglycemia. It is determined that a pituitary adenoma is the cause of these symptoms. Adrenal examination is expected to show?

Diffuse hyperplasia of the adrenal cortex

step1

B

You are interested in examining the prevalence of a highly contagious viral disease over a time period of 5 years. The virus appears to be indigenous to rural parts of northern Africa. Which of the following research study designs would be optimal for your analysis?

Cohort study

step2&3

D

A 9-year-old boy is brought to the clinic by his dad for an annual well-child exam. The boy was diagnosed with ADHD at an outside clinic and has been on methylphenidate for symptom management for the past year. The father reports that the patient is more energetic but that his teacher still complains of him "spacing out" during class. The patient reports that it is difficult to follow in class sometimes because the teacher would just “skip ahead suddenly.” He denies any headaches, vision changes, fever, or abdominal pain, but endorses decreased appetite since starting methylphenidate. What is the mechanism of action of the drug that is the most appropriate for this patient at this time?

Blockage of thalamic T-type calcium channels

step1

B

A 17-year-old girl suddenly grabs her chest and collapses to the ground while playing volleyball at school. The teacher rushes to evaluate the situation and finds that the girl has no pulse and is not breathing. He starts chest compressions. An automated external defibrillator (AED) is brought to the scene within 3 minutes and a shock is delivered. The girl regains consciousness and regular sinus rhythm. She is rushed to the emergency department. The vital signs include: blood pressure 122/77 mm Hg and pulse 65/min. The pulse is regular. An electrocardiogram (ECG) shows a shortened PR interval, a wide QRS complex, a delta wave, and an inverted T wave. Which of the following is the most likely pathology in the conduction system of this patient’s heart?

Accessory pathway from atria to ventricles

step1

D

A 68-year-old woman comes to the emergency department because of abdominal pain for 3 days. Physical examination shows guarding and tenderness to palpation over the left lower abdomen. Test of the stool for occult blood is positive. A CT scan of the abdomen is shown. Which of the following mechanisms best explains the patient's imaging findings?

Impaired organ ascent

step1

E

A 73-year-old man presents to his primary care physician complaining of increased urinary frequency, nocturia, and incomplete emptying after void. He is otherwise healthy, with no active medical problems. On examination, a large, symmetric, firm, smooth prostate is palpated, but otherwise the exam is normal. Which of the following is a potential complication of the patient's present condition?

Hydronephrosis

step2&3

B

A 34-year-old female visits her primary care physician because recently she has started to have painful, numb, and discolored toes. She is otherwise healthy and has no family history of similar conditions that she can recall. Occasionally during these episodes, her fingers and nose will also have similar symptoms. On examination, the patient's appearance is completely normal with warm and well perfused extremities. No evidence of discoloration is found. On closer questioning, she reveals that several months ago during the summer, she succumbed to a viral illness that caused her to feel fatigued and have a long bout of cold symptoms with sore throat and swollen lymph nodes. The bacterial species that is also associated with this patient's most likely condition has which of the following characteristics?

No cell wall

step1

D

A 76-year-old man is brought to the emergency department by his daughter because he has been feeling lightheaded and almost passed out during dinner. Furthermore, over the past few days he has been experiencing heart palpitations. His medical history is significant for well-controlled hypertension and diabetes. Given this presentation, an electrocardiogram is performed showing an irregularly irregular tachyarrhythmia with narrow QRS complexes. The patient is prescribed a drug that decreases the slope of phase 0 of the ventricular action potential but does not change the overall duration of the action potential. Which of the following drugs is consistent with this mechanism of action?

Propafenone

step1

D

A 15-year-old high school rugby player presents to your clinic with a sore throat. He reports that he started feeling fatigued along with body aches about a week ago. His vitals and physical are normal except for an exudative pharynx and an enlarged spleen. Monospot test comes back positive and the student is told not to participate in contact sports for a month. What is the most likely causative agent and which immune cell does it affect?

Epstein-Barr virus; B-cells

step1

B

A 27-year-old man is brought to the emergency department by ambulance following a motor vehicle accident 1 hour prior. He appears agitated. His blood pressure is 85/60 mm Hg, the pulse is 110/min, and the respiratory rate is 19/min. Physical examination shows bruising of the left flank and fracture of the left lower thoracic bones. Strict bed rest and monitoring with intravenous fluids is initiated. Urinalysis shows numerous RBCs. A contrast-enhanced CT scan shows normal enhancement of the right kidney. The left renal artery is only visible in the proximal section with a small amount of extravasated blood around the left kidney. The left kidney shows no enhancement. Imaging of the spleen shows no abnormalities. Which of the following is the most appropriate next step in management?

Immediate surgical exploration

step2&3

B

A 67-year-old man presents to the surgical clinic with swelling of his right leg, fever, and chills for 2 days. The maximum recorded temperature was 38.3°C (101.0°F) at home. His right leg is red and swollen from the dorsum of the foot to the thigh with an ill-defined edge. Venous stasis ulcers are present in both of his limbs, but those on the right have a yellow discharge. His vitals include the following: blood pressure is 120/78 mm Hg, heart rate is 94/min, temperature is 38.3°C (101.0°F), and respiratory rate is 16/min. On physical examination, there is tenderness and warmth compared with his normal leg. Dorsalis pedis pulses are present on both of the ankles. What is the most likely cause of the right shift of the hemoglobin dissociation curve for his condition?

Increase in temperature

step1

C

A 36-year-old Caucasian woman is referred to the outpatient clinic by a physician at a health camp for 6-months of foul-smelling diarrhea with bulky and floating stools as well as significant flatulence which makes her extremely uncomfortable at work and social events. She has concomitant weight loss and recently fractured her wrist in a seemingly insignificant fall from her own height. Vital signs are normal and a physical examination shows grouped, papulovesicular, pruritic skin lesions, as well as areas of hypoesthesia in the hands and feet. Which of the following would be most useful in this case?

Anti-tissue transglutaminase antibodies

step2&3

A

A 58-year-old woman with a history of breast cancer, coronary artery disease, gastroesophageal reflux, and diabetes mellitus is diagnosed with angiosarcoma. Which of the following most likely predisposed her to this condition?

History of mastectomy with lymph node dissection

step1

D

A 38-year-old man with chronic hepatitis C comes to the physician because of a 10-day history of darkening of his skin and painless blisters. He started working as a landscaper 2 weeks ago. He drinks 2 beers every night and occasionally more on the weekends. Examination shows bullae and oozing erosions in different stages of healing on his arms, dorsal hands, and face. There are atrophic white scars and patches of hyperpigmented skin on the arms and face. This patient's skin findings are most likely associated with increased concentration of which of the following?

Uroporphyrinogen III

step1

D

A 20-year-old man presents to the emergency department by his father for not sleeping for 2 nights consecutively. His father noticed that the patient has been in an unusual mood. One day ago, the patient disrobed in front of guests after showering. He has also had lengthy conversations with strangers. One month ago, the patient took out a large loan from a bank in order to fund a business idea he has not yet started. He also borrowed his father's credit card to make a spontaneous trip to Switzerland by himself for a few days, where he spent over 30,000 dollars. His father notes that there have been episodes where he would not leave his bed and remained in his room with the lights off. During these episodes, he sleeps for approximately 15 hours. On physical exam, he is talkative, distractable, and demonstrates a flight of ideas. His speech is pressured, difficult to interrupt, and he asks intrusive questions. Which of the following is the best treatment option for this patient?

Lithium

step2&3

D

A 27-year-old woman comes to the physician because she has been hearing voices in her apartment during the past year. She also reports that she has been receiving warning messages in newspaper articles during this period. She thinks that “someone is trying to kill her”. She avoids meeting her family and friends because they do not believe her. She does not use illicit drugs. Physical examination shows no abnormalities. Mental status examination shows a normal affect. Which of the following is the most appropriate long-term treatment?

Quetiapine

step1

A

A 26-year-old woman presents to the emergency department for shortness of breath. She was walking up a single flight of stairs when she suddenly felt short of breath. She was unable to resolve her symptoms with use of her albuterol inhaler and called emergency medical services. The patient has a past medical history of asthma, constipation, irritable bowel syndrome, and anxiety. Her current medications include albuterol, fluticasone, loratadine, and sodium docusate. Her temperature is 99.5°F (37.5°C), blood pressure is 110/65 mmHg, pulse is 100/min, respirations are 24/min, and oxygen saturation is 85% on room air. On physical exam the patient demonstrates poor air movement and an absence of wheezing. The patient is started on an albuterol nebulizer. During treatment, the patient's saturation drops to 72% and she is intubated. The patient is started on systemic steroids. A Foley catheter and an orogastric tube are inserted, and the patient is transferred to the MICU. The patient is in the MICU for the next seven days. Laboratory values are ordered as seen below. Hemoglobin: 11 g/dL Hematocrit: 33% Leukocyte count: 9,500 cells/mm^3 with normal differential Platelet count: 225,000/mm^3 Serum: Na+: 140 mEq/L Cl-: 102 mEq/L K+: 4.0 mEq/L HCO3-: 24 mEq/L BUN: 21 mg/dL Glucose: 129 mg/dL Creatinine: 1.2 mg/dL Ca2+: 10.1 mg/dL AST: 22 U/L ALT: 19 U/L Urine: Color: amber Nitrites: positive Leukocytes: positive Sodium: 12 mmol/24 hours Red blood cells: 0/hpf Which of the following measures would have prevented this patient's laboratory abnormalities?

Intermittent catheterization

step2&3

E

A 42-year-old woman comes to the physician because of episodic abdominal pain and fullness for 1 month. The pain extends from the epigastrium to the right upper quadrant. Episodes last up to 2 hours and are not aggravated by eating. She describes the pain as 5 out of 10 in intensity. She has severe nausea and had 6 episodes of vomiting over the last 3 days. She works as an assistant at an animal shelter, helping to feed and bathe the animals. Her temperature is 37.3°C (99.1°F), pulse is 87/min, and blood pressure is 100/60 mm Hg. Examination shows a palpable 4-cm, smooth mass below the right costal margin; it is nontender and moves with respiration. The remainder of the examination shows no abnormalities. Laboratory studies show: Hemoglobin 13.2 Leukocyte count 6800/mm3 Segmented neutrophils 60% Eosinophils 6% Lymphocytes 30% Monocytes 4% Bilirubin (total) 0.9 mg/dL An ultrasound image of the abdomen shows a unilocular cyst 4 cm in diameter with daughter cysts within the liver. Which of the following is the most appropriate next step in management?"

Oral albendazole

step2&3

E

A 3-year-old boy is brought to the physician because of a 3-day history of fever and chills. The mother reports that he has also been limping for 2 days. He has no history of trauma to this region. His temperature is 38.9°C (102°F). Physical examination shows dull tenderness over his left lower extremity. The range of motion of the leg is also limited by pain. While walking, he avoids putting weight on his left leg. Laboratory studies show an erythrocyte sedimentation rate of 67 mm/h. An MRI is most likely to show abnormalities in which of the following regions?

Proximal metaphysis of the femur

step1

B

A 1-year-old boy presents to the physician with a fever and a persistent cough for the past 5 days. His parents noted that since birth, he has had a history of recurrent skin infections, ear infections, and episodes of pneumonia with organisms including Staphylococcus aureus, Pseudomonas, and Candida. Physical exam is notable for prominent facial scars in the periorbital and nasal regions, which his parents explain are a result of healed abscesses from previous skin infections. A sputum sample is obtained from the patient and the culture grows Aspergillus. Which of the following diagnostic test findings would confirm the patient’s underlying genetic disease?

Dihydrorhodamine test

step2&3

B

Three days after being admitted to the hospital because of a fall from the roof of a two-story building, a 27-year-old man is being monitored in the intensive care unit. On arrival, the patient was somnolent and not oriented to person, place, or time. A CT scan of the head showed an epidural hemorrhage that was 45 cm3 in size and a midline shift of 7 mm. Emergency surgery was performed with craniotomy and hematoma evacuation on the day of admission. Perioperatively, a bleeding vessel was identified and ligated. Postoperatively, the patient was transferred to the intensive care unit and placed on a ventilator. His temperature is 37°C (98.6°F), pulse is 67/min, and blood pressure is 117/78 mm Hg. The ventilator is set at a FiO2 of 55%, tidal volume of 520 mL, and positive end-expiratory pressure of 5.0 cm H2O. In addition to intravenous administration of fluids, which of the following is the most appropriate next step in managing this patient's nutrition?

Enteral feeding via nasogastric tube

step2&3

D

A 50-year-old man presents to the emergency department due to altered mental status. His symptoms began approximately two weeks prior to presentation where he complained of increasing fatigue, malaise, loss of appetite, and subjective fever. Vital signs are significant for a temperature of 102.0°F (38.9°C). On physical examination, there is a holosystolic murmur in the tricuspid area, linear non-blanching reddish lesions under the nails, and needle tracks on both antecubital fossa. A transthoracic echocardiogram shows a vegetation on the tricuspid valve. Blood cultures return positive for Staphylococcus aureus. A lumbar puncture is prompted due to altered mental status in the setting of fever; however, there is no bacteria found on cerebral spinal fluid (CSF) culture. Which of the following cell structures prevents the penetration of the bacteria into the CSF from his blood?

Tight junctions

step1

C

A 3-year-old boy is diagnosed with an alpha-gal allergy, also known as mammalian meat allergy (MMA). This condition is mediated by a reaction to the carbohydrate, galactose-alpha-1,3-galactose. An experimental treatment has been developed to halt the N-linked oligosaccharide addition that occurs in the synthesis of this compound. Which of the following cellular structures is most likely targeted by this experimental drug?

Rough endoplasmic reticulum

step1

B