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Six hours after delivery, a 3050-g (6-lb 12-oz) male newborn is noted to have feeding intolerance and several episodes of bilious vomiting. He was born at term to a healthy 35-year-old woman following a normal vaginal delivery. The pregnancy was uncomplicated, but the patient's mother had missed several of her prenatal checkups. The patient's older brother underwent surgery for pyloric stenosis as an infant. Vital signs are within normal limits. Physical examination shows epicanthus, upward slanting of the eyelids, low-set ears, and a single transverse palmar crease. The lungs are clear to auscultation. A grade 2/6 holosystolic murmur is heard at the left mid to lower sternal border. Abdominal examination shows a distended upper abdomen and a concave-shaped lower abdomen. There is no organomegaly. An x-ray of the abdomen is shown. Which of the following is the most likely diagnosis?

Duodenal atresia

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B

A researcher is examining the relationship between socioeconomic status and IQ scores. The IQ scores of young American adults have historically been reported to be distributed normally with a mean of 100 and a standard deviation of 15. Initially, the researcher obtains a random sampling of 300 high school students from public schools nationwide and conducts IQ tests on all participants. Recently, the researcher received additional funding to enable an increase in sample size to 2,000 participants. Assuming that all other study conditions are held constant, which of the following is most likely to occur as a result of this additional funding?

Decrease in standard error of the mean

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C

A 27-year-old male presents to his primary care physician complaining of pain with urination and eye redness. He reports that he developed these symptoms approximately one week ago. He also has noticed left knee and right heel pain that started a few days ago. He denies any recent trauma. He had an episode of abdominal pain and diarrhea ten days ago that resolved. He has otherwise felt well. On exam, he walks with a limp and his conjunctivae are erythematous. Laboratory findings are notable for an elevated erythrocyte sedimentation rate (ESR) and elevated C-reactive protein (CRP). Which of the following is most likely associated with this patient’s condition?

HLA-B27 haplotype

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A

A 4-year-old boy is brought to the pediatrician by his mother for a routine medical examination. His medical history is relevant for delayed gross motor milestones. The mother is concerned about a growth delay because both of his brothers were twice his size at this age. Physical examination reveals a well-groomed and healthy boy with a prominent forehead and short stature, in addition to shortened upper and lower extremities with a normal vertebral column. The patient’s vitals reveal: temperature 36.5°C (97.6°F); pulse 60/min; and respiratory rate 17/min and a normal intelligence quotient (IQ). A mutation in which of the following genes is the most likely cause underlying the patient’s condition?

Fibroblast growth factor receptor 3

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C

An investigator is studying brachial artery reactivity in women with suspected coronary heart disease. The brachial artery diameter is measured via ultrasound before and after intra-arterial injection of acetylcholine. An increase of 7% in the vascular diameter is noted. The release of which of the following is most likely responsible for the observed effect?

Nitric oxide from endothelial cells

step1

A

A 28-year-old female in the 2nd trimester of pregnancy is diagnosed with primary Toxoplasma gondii infection. Her physician fears that the fetus may be infected in utero. Which of the following are associated with T. gondii infection in neonates?

Hydrocephalus, chorioretinitis, intracranial calcifications

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E

A 62-year-old man comes to the physician because of a swollen and painful right knee for the last 3 days. He has no history of joint disease. His vital signs are within normal limits. Examination shows erythema and swelling of the right knee, with limited range of motion due to pain. Arthrocentesis of the right knee joint yields 7 mL of cloudy fluid with a leukocyte count of 29,000/mm3 (97% segmented neutrophils). Compensated polarized light microscopy of the aspirate is shown. Which of the following is the most likely underlying mechanism of this patient's knee pain?

Calcium pyrophosphate deposition

step1

B

A new treatment for hemorrhagic stroke, which is a life-threatening clinical condition that occurs when a diseased blood vessel in the brain ruptures or leaks, was evaluated as soon as it hit the market by an international group of neurology specialists. In those treated with the new drug, a good outcome was achieved in 30%, while those treated with the current standard of care had a good outcome in just 10% of cases. The clinicians involved in this cohort study concluded that the newer drug is more effective and prompted for urgent changes in the guidelines addressing hemorrhagic stroke incidents. According to the aforementioned percentages, how many patients must be treated with the new drug to see 1 additional good outcome?

5

step1

A

A 54-year-old man is brought to the emergency department 1 hour after the sudden onset of shortness of breath, epigastric pain, and sweating. He has no history of similar symptoms. He has hypertension and type 2 diabetes mellitus. Current medications include amlodipine and metformin. He has smoked one pack of cigarettes daily for 20 years. He appears weak and pale. His pulse is 56/min, respirations are 18/min, and blood pressure is 100/70 mm Hg. Cardiac examination shows normal heart sounds. The lungs are clear to auscultation. The skin is cold to the touch. An ECG is shown. Bedside transthoracic echocardiography shows normal left ventricular function. High-dose aspirin is administered. Administration of which of the following is most appropriate next step in management?

Normal saline bolus "

step2&3

E

An investigator studying targeted therapy in patients with gastrointestinal stromal tumors requires a reliable test to determine the spatial distribution of CD117-positive cells in biopsy specimens. Which of the following is the most appropriate test?

Immunohistochemistry

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B

In an attempt to create other selective dopamine 1 (D1) agonists, a small pharmaceutical company created a cell-based chemical screen that involved three modified receptors - alpha 1 (A1), beta 1 (B1), and D1. In the presence of D1 stimulation, the cell would produce an mRNA that codes for a fluorescent protein; however, if the A1 or B1 receptors are also stimulated at the same time, the cells would degrade the mRNA of the fluorescent protein thereby preventing it from being produced. Which of the following would best serve as a positive control for this experiment?

Fenoldopam

step1

E

A 56-year-old woman comes to the physician because of a 2-year-history of intermittent upper abdominal pain that occurs a few hours after meals and occasionally wakes her up in the middle of the night. She reports that the pain is relieved with food intake. Physical examination shows no abnormalities. Endoscopy shows a 0.5 x 0.5 cm ulcer on the posterior wall of the duodenal bulb. A biopsy specimen obtained from the edge of the ulcer shows hyperplasia of submucosal glandular structures. Hyperplasia of these cells most likely results in an increase of which of the following?

Bicarbonate secretion

step1

E

The balance between glycolysis and gluconeogenesis is regulated at several steps, and accumulation of one or more products/chemicals can either promote or inhibit one or more enzymes in either pathway. Which of the following molecules if increased in concentration can promote gluconeogenesis?

Acetyl-CoA

step1

E

A 37-year-old man who had undergone liver transplantation 7 years ago, presents to the physician because of yellowish discoloration of the skin, sclera, and urine. He is on regular immunosuppressive therapy and is well-adherent to the treatment. He has no comorbidities and is not taking any other medication. He provides a history of similar episodes of yellowish skin discoloration 6–7 times since he underwent liver transplantation. Physical examination shows clinical jaundice. Laboratory studies show: While blood cell (WBC) count 4,400/mm3 Hemoglobin 11.1 g/dL Serum creatinine 0.9 mg/dL Serum bilirubin (total) 44 mg/dL Aspartate transaminase (AST) 1,111 U/L Alanine transaminase (ALT) 671 U/L Serum gamma-glutamyl transpeptidase 777 U/L Alkaline phosphatase 888 U/L Prothrombin time 17 seconds A Doppler ultrasound shows significantly reduced blood flow into the transplanted liver. A biopsy of the transplanted liver is likely to show which of the following histological features?

Interstitial cellular infiltration with parenchymal fibrosis, obliterative arteritis

step2&3

E

A 14-year-old girl is brought to the physician after she accidentally cut her right forearm earlier that morning while working with her mother's embroidery scissors. She has no history of serious illness. The mother says she went to elementary and middle school abroad and is not sure if she received all of her childhood vaccinations. She appears healthy. Her temperature is 37°C (98.6 °F), pulse 90/min, and blood pressure is 102/68 mm Hg. Examination shows a clean 2-cm laceration on her right forearm with surrounding edema. There is no erythema or discharge. The wound is irrigated with water and washed with soap. Which of the following is the most appropriate next step in management?

Administer Tdap only

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C

A 27-year-old woman comes to the physician because of a 3-day history of a sore throat and fever. Her temperature is 38.5°C (101.3°F). Examination shows edematous oropharyngeal mucosa and enlarged tonsils with purulent exudate. There is tender cervical lymphadenopathy. If left untreated, which of the following conditions is most likely to occur in this patient?

Dilated cardiomyopathy

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D

A 72-year-old man comes to his primary care provider because of double vision and headache. He says these symptoms developed suddenly last night and have not improved. He has had type 2 diabetes mellitus for 32 years and essential hypertension for 19 years for which he takes metformin and lisinopril. His last recorded A1c was 9.4%. He has smoked 10 to 15 cigarettes a day for the past 35 years. Family history is significant for chronic kidney disease in his mother. Vital signs reveal a temperature of 36.9 °C (98.42°F), blood pressure of 137/82 mm Hg, and pulse of 72/min. On examination, there is ptosis of the right eye and it is deviated down and out. Visual acuity is not affected in either eye. Which of the following cranial nerves is most likely impaired in this patient?

Oculomotor nerve

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B

A 3-year-old boy is brought to the emergency department with abdominal pain. His father tells the attending physician that his son has been experiencing severe stomach aches over the past week. They are intermittent in nature, but whenever they occur he cries and draws up his knees to his chest. This usually provides some relief. The parents have also observed mucousy stools and occasional bloody stools that are bright red with blood clots. They tell the physician that their child has never experienced this type of abdominal pain up to the present. 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. On physical exam, his vitals are generally normal with a slight fever and mild tachycardia. The boy appears uncomfortable. An abdominal exam reveals a sausage-shaped mass in the right upper abdomen. Which of the following is the most common cause of these symptoms?

Idiopathic

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E

A 51-year-old man presents complaining of decreased vibratory sense in his lower limbs. Physical exam reveals a widened pulse pressure and a decrescendo murmur occurring after the S2 heart sound. After further questioning, he also reports he experienced a maculopapular rash over his trunk, palms and soles many years ago that resolved on its own. In order to evaluate the suspected diagnosis, the physician FIRST tested for which of the following?

Agglutination of antibodies with beef cardiolipin

step1

A

A 28-year-old woman comes to the physician for genetic counseling prior to conception. For the past year, she has had intermittent episodes of headache, nausea, abdominal pain, and tingling of her fingers. She also complains of dark urine during the episodes. Her mother and maternal uncle have similar symptoms and her father is healthy. Her husband is healthy and there is no history of serious illness in his family. Serum studies show elevated concentrations of porphobilinogen and δ-aminolevulinic acid. What is the probability of this patient having a child with the same disease as her?

50%

step1

B

Three days after undergoing cardiac catheterization and coronary angioplasty for acute myocardial infarction, a 70-year-old man develops shortness of breath at rest. He has hypertension, hyperlipidemia, and type 2 diabetes mellitus. His current medications include aspirin, clopidogrel, atorvastatin, sublingual nitroglycerin, metoprolol, and insulin. He appears diaphoretic. His temperature is 37°C (98.6°F), pulse is 120/min, respirations are 22/min, and blood pressure is 100/55 mm Hg. Crackles are heard at both lung bases. Cardiac examination shows a new grade 3/6 holosystolic murmur heard best at the cardiac apex. An ECG shows sinus rhythm with T wave inversion in leads II, III, and aVF. Which of the following is the most likely explanation for this patient's symptoms?

Papillary muscle rupture

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E

An investigator is studying the mechanism of HIV infection in cells obtained from a human donor. The effect of a drug that impairs viral fusion and entry is being evaluated. This drug acts on a protein that is cleaved off of a larger glycosylated protein in the endoplasmic reticulum of the host cell. The protein that is affected by the drug is most likely encoded by which of the following genes?

env

step1

D

A 54-year-old man comes to the physician for a follow-up examination. One week ago, he was treated in the emergency department for chest pain, palpitations, and dyspnea. As part of his regimen, he was started on a medication that irreversibly inhibits the synthesis of thromboxane A2 and prostaglandins. Which of the following is the most likely adverse effect of this medication?

Gastrointestinal hemorrhage

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E

A 66-year-old man undergoes a coronary artery bypass grafting. Upon regaining consciousness, he reports that he cannot see from either eye and cannot move his arms. Physical examination shows bilaterally equal, reactive pupils. A fundoscopy shows no abnormalities. An MRI of the brain shows wedge-shaped cortical infarcts in both occipital lobes. Which of the following is the most likely cause of this patient's current symptoms?

Systemic hypotension "

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E

A 74-year-old man presents to the emergency room with abdominal pain. He reports acute onset of left lower quadrant abdominal pain and nausea three hours prior to presentation. The pain is severe, constant, and non-radiating. He has had two maroon-colored bowel movements since the pain started. His past medical history is notable for hypertension, hyperlipidemia, atrial fibrillation, insulin-dependent diabetes mellitus, and rheumatoid arthritis. He takes lisinopril, hydrochlorothiazide, atorvastatin, dabigatran, methotrexate. He has a 60 pack-year smoking history and drinks 1-2 beers per day. He admits to missing some of his medications recently because he was on vacation in Hawaii. His last colonoscopy was 4 years ago which showed diverticular disease in the descending colon and multiple sessile polyps in the sigmoid colon which were removed. His temperature is 100.1°F (37.8°C), blood pressure is 145/85 mmHg, pulse is 100/min, and respirations are 20/min. On exam, he has notable abdominal distention and is exquisitely tender to palpation in all four abdominal quadrants. Bowel sounds are absent. Which of the following is the most likely cause of this patient’s condition?

Cardiac thromboembolism

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A

A 7-year-old boy is brought to the physician by his father because of a 1-day history of a pruritic rash on his trunk and face. Five days ago, he developed low-grade fever, nausea, and diarrhea. Physical examination shows a lace-like erythematous rash on the trunk and face with circumoral pallor. The agent most likely causing symptoms in this patient has selective tropism for which of the following cells?

Erythroid progenitor cells

step1

C

A 43-year-old woman presents to your clinic for the evaluation of an abnormal skin lesion on her forearm. The patient is worried because her mother passed away from melanoma. You believe that the lesion warrants biopsy for further evaluation for possible melanoma. Your patient is concerned about her risk for malignant disease. What is the most important prognostic factor of melanoma?

Depth of invasion of atypical cells

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D

A 30-year-old woman presents to her physician for her annual checkup. She has diabetes mellitus, type 1 and takes insulin regularly. She reports no incidents of elevated or low blood sugar and that she is feeling energetic and ready to face the morning every day. Her vital signs and physical are normal. On the way home from her checkup she stops by the pharmacy and picks up her prescription of insulin. Later that night she takes a dose. What is the signaling mechanism associated with this medication?

Activation of tyrosine kinase

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C

A 14-year-old girl comes to the physician because of excessive flow and duration of her menses. Since menarche a year ago, menses have occurred at irregular intervals and lasted 8–9 days. Her last menstrual period was 5 weeks ago with passage of clots. She has no family or personal history of serious illness and takes no medications. She is at the 50th percentile for height and 20th percentile for weight. Physical examination shows no abnormalities. A urine pregnancy test is negative. Which of the following is the most likely cause of this patient's symptoms?

Inadequate gonadotropin production

step2&3

C

A 3-week-old boy is brought to the pediatrician by his parents for a circumcision. The circumcision was uncomplicated; however, after a few hours, the diaper contained blood, and the bleeding has not subsided. A complete blood count was ordered, which was significant for a platelet count of 70,000/mm3. On peripheral blood smear, the following was noted (figure A). The prothrombin time was 12 seconds, partial thromboplastin time was 32 seconds, and bleeding time was 13 minutes. On platelet aggregation studies, there was no response with ristocetin. This result was not corrected with the addition of normal plasma. There was a normal aggregation response with the addition of ADP. Which of the following is most likely true of this patient's underlying disease?

Decreased GpIb

step1

D

A 57-year-old man presents to the emergency department with shortness of breath. He was eating dinner with his family during the holidays and felt very short of breath, thus prompting him to come in. The patient has a past medical history of diabetes, hypertension, 2 myocardial infarctions, and obesity. Physical exam is notable for bilateral pulmonary crackles and a jugular venous distension. Chest radiography reveals an enlarged cardiac silhouette and blunting of the costophrenic angles. The patient is started on a medication for his acute symptoms. Two hours later, he states his symptoms have vastly improved and repeat chest radiography is notable for an enlarged cardiac silhouette. Which of the following is a property of the medication most likely given?

Chronic use leads to long-term nephrogenic adaptations

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E

A 47-year-old woman presents to her physician for difficulty swallowing. She states that she intentionally delayed seeing a physician for this issue. She says her primary issue with swallowing is that her mouth always feels dry so she has difficulty chewing food to the point that it can be swallowed. On physical examination, her oral mucosa appears dry. Both of her eyes also appear dry. Several enlarged lymph nodes are palpated. Which of the following patterns of reactive lymphadenitis is most commonly associated with this patient’s presentation?

Follicular hyperplasia

step1

B

A 45-year-old female is admitted to the hospital after worsening headaches for the past month. She has noticed that the headaches are usually generalized, and frequently occur during sleep. She does not have a history of migraines or other types of headaches. Her past medical history is significant for breast cancer, which was diagnosed a year ago and treated with mastectomy. She recovered fully and returned to work shortly thereafter. CT scan of the brain now shows a solitary cortical 5cm mass surrounded by edema in the left hemisphere of the brain at the grey-white matter junction. She is admitted to the hospital for further management. What is the most appropriate next step in management for this patient?

Surgical resection of the mass

step2&3

E

A 42-year-old woman comes to the physician because of progressive weakness. She has noticed increasing difficulty performing household chores and walking her dog over the past month. Sometimes she feels too fatigued to cook dinner. She has noticed that she feels better after sleeping. She does not have chest pain, shortness of breath, or a history of recent illness. She has no personal history of serious illness and takes no medications. She has smoked two packs of cigarettes daily for 25 years. She appears fatigued. Her temperature is 37°C (98.8°F), pulse is 88/min, and blood pressure is 148/80 mm Hg. Pulse oximetry shows an oxygen saturation of 98% in room air. Bilateral expiratory wheezes are heard at both lung bases. Examination shows drooping of the upper eyelids. There is diminished motor strength in her upper extremities. Her sensation and reflexes are intact. A treatment with which of the following mechanisms of action is most likely to be effective?

Inhibition of acetylcholinesterase

step2&3

A

An investigator is studying cardiomyocytes in both normal and genetically modified mice. Both the normal and genetically modified mice are observed after aerobic exercise and their heart rates are recorded and compared. After a 10-minute session on a treadmill, the average pulse measured in the normal mice is 680/min, whereas in the genetically modified mice it is only 160/min. Which of the following is most likely to account for the increased heart rate seen in the normal mice?

Greater T-tubule density

step1

E

A 54-year-old man presents to his primary care physician with a 2-month-history of diarrhea. He says that he feels the urge to defecate 3-4 times per day and that his stools have changed in character since the diarrhea began. Specifically, they now float, stick to the side of the toilet bowl, and smell extremely foul. His past medical history is significant for several episodes of acute pancreatitis secondary to excessive alcohol consumption. His symptoms are found to be due to a deficiency in an enzyme that is resistant to bile salts. Which of the following enzymes is most likely deficient in this patient?

Colipase

step1

C

A 50-year-old woman comes to the physician because of worsening pain and swelling of her left knee. For the past year, she has had pain in her knees and hands bilaterally, but never this severe. During this period, she has also had difficulties moving around for about an hour in the mornings and has been sweating more than usual, especially at night. She has been sexually active with a new partner for the past 4 weeks, and they use condoms inconsistently. She occasionally drinks alcohol. The day before she drank 6 beers because she was celebrating a friend's birthday. Her temperature is 38.5°C (101.3°F), blood pressure is 110/70 mm Hg, and pulse is 92/min. The left knee is erythematous, swollen, and tender; movement is restricted due to pain. There is swelling of the metacarpophalangeal joints and proximal interphalangeal joints bilaterally. Arthrocentesis of the knee with synovial fluid analysis shows a greenish, turbid fluid, a cell count of 68,000 WBC/μL and Gram-negative diplococci. An x-ray of the affected knee is most likely to show which of the following findings?

Joint space narrowing and bone erosions

step2&3

E

A 35-year-old woman, gravida 2, para 1, at 16 weeks' gestation comes to the office for a prenatal visit. She reports increased urinary frequency but otherwise feels well. Pregnancy and delivery of her first child were uncomplicated. Her vital signs are within normal limits. Pelvic examination shows a uterus consistent in size with a 16-week gestation. Urinalysis shows mild glucosuria. Laboratory studies show a non-fasting serum glucose concentration of 110 mg/dL. Which of the following is the most likely explanation for this patient's glucosuria?

Increased glomerular filtration rate

step1

E

A 10-month-old boy is referred to the hospital because of suspected severe pneumonia. During the first month of his life, he had developed upper airway infections, bronchitis, and diarrhea. He has received all the immunizations according to his age. He failed to thrive since the age of 3 months. A month ago, he had a severe lung infection with cough, dyspnea, and diarrhea, and was unresponsive to an empiric oral macrolide. Upon admission to his local hospital, the patient has mild respiratory distress and crackles on auscultation. The temperature is 39.5°C (103.1°F), and the oxygen saturation is 95% on room air. The quantitative immunoglobulin tests show increased IgG, IgM, and IgA. The peripheral blood smear shows leukocytosis and normochromic normocytic anemia. The chloride sweat test and tuberculin test are negative. The chest X-ray reveals bilateral pneumonia. The bronchoalveolar lavage and gram stain report gram-negative bacteria with a growth of Burkholderia cepacia on culture. The laboratory results on admission are as follows: Leukocytes 36,600/mm3 Neutrophils 80% Lymphocytes 16% Eosinophils 1% Monocytes 2% Hemoglobin 7.6 g/dL Creatinine 0.8 mg/dL BUN 15 mg/dL Which of the following defects of neutrophil function is most likely responsible?

Absent respiratory burst

step1

A

A 74-year-old man presents to the physician with a painful lesion over his right lower limb which began 2 days ago. He says that the lesion began with pain and severe tenderness in the area. The next day, the size of the lesion increased and it became erythematous. He also mentions that a similar lesion had appeared over his left lower limb 3 weeks earlier, but it disappeared after a few days of taking over the counter analgesics. There is no history of trauma, and the man does not have any known medical conditions. On physical examination, the physician notes a cordlike tender area with erythema and edema. There are no signs suggestive of deep vein thrombosis or varicose veins. Which of the following malignancies is most commonly associated with the lesion described in the patient?

Adenocarcinoma of pancreas

step1

E

A 53-year-old man is being evaluated for a 3-week history of fatigue, difficulty to concentrate, dyspnea with exertion, dizziness, and digital pain that improves with cold. He has smoked half a pack of cigarettes a day since he was 20. His current medical history involves hypertension. He takes enalapril daily. The vital signs include a blood pressure of 131/82 mm Hg, a heart rate of 95/min, and a temperature of 36.9°C (98.4°F). On physical examination, splenomegaly is found. A complete blood count reveals thrombocytosis of 700,000 cells/m3. Lab work further shows decreased serum iron, iron saturation, and serum ferritin and increased total iron binding capacity. A blood smear reveals an increased number of abnormal platelets, and a bone marrow aspirate confirmed the presence of dysplastic megakaryocytes. A mutation on his chromosome 9 confirms the physician’s suspicion of a certain clonal myeloproliferative disease. The patient is started on hydroxyurea. What is the most likely diagnosis?

Essential thrombocythemia

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B

A 50-year-old Caucasian man presents for a routine checkup. He does not have any current complaint. He is healthy and takes no medications. He has smoked 10–15 cigarettes per day for the past 10 years. His family history is negative for gastrointestinal disorders. Which of the following screening tests is recommended for this patient according to the United States Preventive Services Task Force (USPSTF)?

Colonoscopy for colorectal cancer

step2&3

E

A 76-year-old man comes to the physician for a follow-up examination. One week ago, he was prescribed azithromycin for acute bacterial sinusitis. He has a history of atrial fibrillation treated with warfarin and metoprolol. Physical examination shows no abnormalities. Compared to one month ago, laboratory studies show a mild increase in INR. Which of the following best explains this patient's laboratory finding?

Depletion of intestinal flora

step1

A

A 2-week-old male newborn is brought to the physician because his mother has noticed her son has occasional bouts of ""turning blue in the face"" while crying. He also tires easily and sweats while feeding. He weighed 2150 g (4 lb 11 oz) at birth and has gained 200 g (7 oz). The baby appears mildly cyanotic. Examination shows a 3/6 systolic ejection murmur heard over the left upper sternal border. A single S2 is present. An echocardiography confirms the diagnosis. Which of the following factors is the main determinant of the severity of this patient's cyanosis?"

Right ventricular outflow obstruction

step1

A

A 19-year-old man presents to an orthopedic surgeon to discuss repair of his torn anterior cruciate ligament. He suffered the injury during a college basketball game 1 week ago and has been using a knee immobilizer since the accident. His past medical history is significant for an emergency appendectomy when he was 12 years of age. At that time, he said that he never wanted to have surgery again. At this visit, the physician explains the procedure to him in detail including potential risks and complications. The patient acknowledges and communicates his understanding of both the diagnosis as well as the surgery and decides to proceed with the surgery in 3 weeks. Afterward, he signs a form giving consent for the operation. Which of the following statements is true about this patient?

He has the right to revoke his consent at any time

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C

A 55-year-old male presents with complaints of intermittent facial flushing. He also reports feeling itchy after showering. On review of systems, the patient says he has been having new onset headaches recently. On physical exam, his vital signs, including O2 saturation, are normal. He has an abnormal abdominal mass palpable in the left upper quadrant. A complete blood count reveals: WBCs 6500/microliter; Hgb 18.2 g/dL; Platelets 385,000/microliter. Which of the following is most likely responsible for his presentation?

Tyrosine kinase mutation

step1

C

A 42-year-old Caucasian male presents to your office with hematuria and right flank pain. He has no history of renal dialysis but has a history of recurrent urinary tract infections. You order an intravenous pyelogram, which reveals multiple cysts of the collecting ducts in the medulla. What is the most likely diagnosis?

Medullary sponge kidney

step1

D

A 28-year-old woman presents with severe vertigo. She also reports multiple episodes of vomiting and difficulty walking. The vertigo is continuous, not related to the position, and not associated with tinnitus or hearing disturbances. She has a past history of acute vision loss in her right eye that resolved spontaneously several years ago. She also experienced left-sided body numbness 3 years ago that also resolved rapidly. She only recently purchased health insurance and could not fully evaluate the cause of her previous symptoms at the time they presented. The patient is afebrile and her vital signs are within normal limits. On physical examination, she is alert and oriented. An ophthalmic exam reveals horizontal strabismus. There is no facial asymmetry and her tongue is central on the protrusion. Gag and cough reflexes are intact. Muscle strength is 5/5 bilaterally. She has difficulty maintaining her balance while walking and is unable to perform repetitive alternating movements with her hands. Which of the following is the best course of treatment for this patient’s condition?

High-doses of corticosteroids

step2&3

D

A 19-year-old man is brought to the emergency department by the resident assistant of his dormitory for strange behavior. He was found locked out of his room, where the patient admitted to attending a fraternity party before becoming paranoid that the resident assistant would report him to the police. The patient appears anxious. His pulse is 105/min, and blood pressure is 142/85 mm Hg. Examination shows dry mucous membranes and bilateral conjunctival injection. Further evaluation is most likely to show which of the following?

Impaired reaction time

step1

E

A 23-year-old primigravid woman comes to the physician at 36 weeks' gestation for her first prenatal visit. She confirmed the pregnancy with a home urine pregnancy kit a few months ago but has not yet followed up with a physician. She takes no medications. Vital signs are within normal limits. Pelvic examination shows a uterus consistent in size with a 36-week gestation. Laboratory studies show: Hemoglobin 10.6 g/dL Serum Glucose 88 mg/dL Hepatitis B surface antigen negative Hepatitis C antibody negative HIV antibody positive HIV load 11,000 copies/mL (N < 1000 copies/mL) Ultrasonography shows an intrauterine fetus consistent in size with a 36-week gestation. Which of the following is the most appropriate next step in management of this patient?"

Start cART and schedule cesarean delivery at 38 weeks' gestation

step2&3

B

A 54-year-old woman comes to the emergency department because of drooping on the left side of her face since that morning. She also reports difficulty closing her eyes and chewing. During the neurologic examination, the physician asks the patient to open her jaw against resistance. Which of the following muscles is most likely activated in this movement?

Lateral pterygoid

step1

A

A 45-year-old female with a history of gastroesophageal reflux disease presents to her family physician with symptoms of epigastric pain right after a meal. The physician performs a urea breath test which is positive and the patient is started on appropriate medical therapy. Three days later at a restaurant, she experienced severe flushing, tachycardia, hypotension, and vomiting after her first glass of wine. Which of the following is the mechanism of action of the medication causing this side effect?

Forms toxic metabolites that damage bacterial DNA

step1

D

A 53-year-old woman presents to your office with several months of fatigue and abdominal pain. The pain is dull in character and unrelated to meals. She has a history of type 2 diabetes mellitus and rheumatic arthritis for which she is taking ibuprofen, methotrexate, and metformin. She has 2-3 drinks on the weekends and does not use tobacco products. On physical examination, there is mild tenderness to palpation in the right upper quadrant. The liver span is 15 cm at the midclavicular line. Laboratory results are as follows: Serum: Na+: 135 mEq/L Cl-: 100 mEq/L K+: 3.7 mEq/L HCO3-: 24 mEq/L BUN: 13 mg/dL Creatinine: 1.0 mg/dL Alkaline phosphatase: 100 U/L AST: 70 U/L ALT: 120 U/L Bilirubin (total): 0.5 mg/dL Bilirubin (conjugated): 0.1 mg/dL Amylase: 76 U/L What is the most likely cause of her clinical presentation?

Fatty infiltration of hepatocytes

step1

B

A 24-year-old man presents with low-grade fever and shortness of breath for the last 3 weeks. Past medical history is significant for severe mitral regurgitation status post mitral valve replacement five years ago. His temperature is 38.3°C (101.0°F) and respiratory rate is 18/min. Physical examination reveals vertical hemorrhages under his nails, multiple painless erythematous lesions on his palms, and two tender, raised nodules on his fingers. Cardiac auscultation reveals a new-onset 2/6 holosystolic murmur loudest at the apex with the patient in the left lateral decubitus position. A transesophageal echocardiogram reveals vegetations on the prosthetic valve. Blood cultures reveal catalase-positive, gram-positive cocci. Which of the following characteristics is associated with the organism most likely responsible for this patient’s condition?

Novobiocin sensitive

step1

E

A 23-year-old woman with asthma is brought to the emergency department because of shortness of breath and wheezing for 20 minutes. She is unable to speak more than a few words at a time. Her pulse is 116/min and respirations are 28/min. Pulse oximetry on room air shows an oxygen saturation of 92%. Examination of the lungs shows decreased breath sounds and scattered end-expiratory wheezing over all lung fields. Treatment with high-dose continuous inhaled albuterol is begun. This patient is at increased risk for which of the following adverse effects?

Hypokalemia

step1

C

A 59-year-old man comes to the physician because of a 4-month history of a pruritic rash. His symptoms have not improved despite treatment with over-the-counter creams. During this period, he has also had a 6-kg (13.5-lb) weight loss. Examination shows a scaly rash over his chest, back, and thighs. A photograph of the rash on his thighs is shown. A biopsy of the skin lesions shows clusters of neoplastic cells with cerebriform nuclei within the epidermis. This patient's condition is most likely caused by the abnormal proliferation of which of the following cell types?

T cells

step1

A

A 6-year-old boy is brought in by his mother to his pediatrician for headache and nausea. His headaches began approximately 3 weeks ago and occur in the morning. Throughout the 3 weeks, his nausea has progressively worsened, and he had 2 episodes of emesis 1 day ago. On physical exam, cranial nerves are grossly intact, and his visual field is intact. The patient has a broad-based gait and difficulty with heel-to-toe walking, as well as head titubation. Fundoscopy demonstrates papilledema. A T1 and T2 MRI of the brain is demonstrated in Figures A and B, respectively. Which of the following is most likely the diagnosis?

Medulloblastoma

step2&3

C

A simple experiment is performed to measure the breakdown of sucrose into glucose and fructose by a gut enzyme that catalyzes this reaction. A glucose meter is used to follow the breakdown of sucrose into glucose. When no enzyme is added to the sucrose solution, the glucose meter will have a reading of 0 mg/dL; but when the enzyme is added, the glucose meter will start to show readings indicative of glucose being formed. Which of the following diabetic pharmacological agents, when added before the addition of the gut enzyme to the sucrose solution, will maintain a reading of 0 mg/dL?

Acarbose

step1

D

Three days into hospitalization for a fractured distal femur, a 33-year-old man develops dyspnea and confusion. He has no history of a serious illness. He is unable to answer any questions or follow any commands. His blood pressure is 145/90 mm Hg, the pulse is 120/min, the respiratory rate is 36/min, and the temperature is 36.7°C (98.1°F). His oxygen saturation is 90% on 80% FiO2. On examination, purpura is noted on the anterior chest, head, and neck. Inspiratory crackles are heard in both lung fields. Arterial blood gas analysis on 80% FiO2 shows: pH 7.54 PCO2 17 mm Hg PO2 60 mm Hg HCO3− 22 mEq/L A chest X-ray is shown. Which of the following best explains the cause of these findings?

Fat embolism

step2&3

B

A 32-year-old woman comes to the emergency department for a 2-week history of right upper quadrant abdominal pain. She has also been feeling tired and nauseous for the past 5 weeks. She has a history of depression and suicidal ideation. She is a social worker for an international charity foundation. She used intravenous illicit drugs in the past but quit 4 months ago. Her only medication is sertraline. Her temperature is 37.8°C (100.0°F), pulse is 100/min, and blood pressure is 128/76 mm Hg. She is alert and oriented. Scleral icterus is present. Abdominal examination shows tenderness to palpation in the right upper quadrant. The liver edge is palpated 3 cm below the right costal margin. There is no rebound tenderness or guarding. The abdomen is non-distended and the fluid wave test is negative. She is able to extend her arms with wrists in full extension and hold them steady without flapping. Laboratory studies show: Hemoglobin 13.8 g/dL Leukocytes 13,700/mm3 Platelets 165,000/mm3 Prothrombin time 14 seconds Partial thromboplastin time 35 seconds Serum: Total bilirubin 4.8 mg/dL Direct bilirubin 1.3 mg/dL Aspartate aminotransferase 1852 U/L Alanine aminotransferase 2497 U/L Urea nitrogen 21 mg/dL Creatinine 1.2 mg/dL Hepatitis A IgM antibody Negative Hepatitis B surface antigen Negative Hepatitis B surface antibody Negative Hepatitis B core IgM antibody Positive Hepatitis C antibody Positive Hepatitis C RNA Negative Urine beta-hCG Negative Which of the following is the most appropriate next step in management?"

Supportive therapy

step2&3

B

A 57-year-old man comes to the physician because of sudden-onset fever, malaise, and pain and swelling of his wrists and ankles that began a week ago. One month ago, he was started on hydralazine for adjunctive treatment of hypertension. His temperature is 37.8°C (100°F). Examination shows swelling, tenderness, warmth, and erythema of both wrists and ankles; range of motion is limited. Further evaluation is most likely to show an increased level of which of the following autoantibodies?

Anti-histone

step1

D

A 64-year-old man who recently immigrated to the United States from Haiti comes to the physician because of a 3-week history of progressively worsening exertional dyspnea and fatigue. For the past few days, he has also had difficulty lying flat due to trouble breathing. Over the past year, he has had intermittent fever, night sweats, and cough but he has not been seen by a physician for evaluation of these symptoms. His temperature is 37.8°C (100°F). An x-ray of the chest is shown. Further evaluation of this patient is most likely to show which of the following findings?

Jugular venous distention on inspiration

step1

D

A 55-year-old man with a past medical history of obesity and hyperlipidemia suddenly develops left-sided chest pain and shortness of breath while at work. He relays to coworkers that the pain is intense and has spread to his upper left arm over the past 10 minutes. He reports it feels a lot like the “heart attack” he had a year ago. He suddenly collapses and is unresponsive. Coworkers perform cardiopulmonary resuscitation for 18 minutes until emergency medical services arrives. Paramedics pronounce him dead at the scene. Which of the following is the most likely cause of death in this man?

Ventricular tachycardia

step1

E

A previously healthy 13-year-old girl is brought to the physician for evaluation of a 2-month history of fatigue. She reports recurrent episodes of pain in her right wrist and left knee. During this period, she has had a 4-kg (8.8-lb) weight loss. Her mother has rheumatoid arthritis. Her temperature is 38°C (100.4°F). Examination shows diffuse lymphadenopathy. Oral examination shows several painless oral ulcers. The right wrist and the left knee are swollen and tender. Laboratory studies show a hemoglobin concentration of 9.8 g/dL, a leukocyte count of 2,000/mm3, and a platelet count of 75,000/mm3. Urinalysis shows excessive protein. This patient's condition is associated with which of the following laboratory findings?

Anti-dsDNA antibodies

step1

B

A 23-year-old man comes to the emergency department because of palpitations, dizziness, and substernal chest pain for three hours. The day prior, he was at a friend’s wedding, where he consumed seven glasses of wine. The patient appears diaphoretic. His pulse is 220/min and blood pressure is 120/84 mm Hg. Based on the patient's findings on electrocardiography, the physician diagnoses atrial fibrillation with rapid ventricular response and administers verapamil for rate control. Ten minutes later, the patient is unresponsive and loses consciousness. Despite resuscitative efforts, the patient dies. Histopathologic examination of the heart at autopsy shows an accessory atrioventricular conduction pathway. Electrocardiography prior to the onset of this patient's symptoms would most likely have shown which of the following findings?

Slurred upstroke of the QRS complex

step1

A

A typically healthy 27-year-old woman presents to the physician because of a 3-week history of fatigue, headache, and dry cough. She does not smoke or use illicit drugs. Her temperature is 37.8°C (100.0°F). Chest examination shows mild inspiratory crackles in both lung fields. An X-ray of the chest shows diffuse interstitial infiltrates bilaterally. A Gram stain of saline-induced sputum shows no organisms. Inoculation of the induced sputum on a cell-free medium that is enriched with yeast extract, horse serum, cholesterol, and penicillin G grows colonies that resemble fried eggs. Which of the following is the most appropriate next step in management?

Oral azithromycin

step2&3

E

A 59-year-old Caucasian man with a history of hypertension and emphysema is brought to the hospital because of progressive lethargy and confusion. The patient has been experiencing poor appetite for the past 3 months and has unintentionally lost 9 kg (19.8 lb). He was a smoker for 35 years and smoked 1 pack daily, but he quit 5 years ago. He takes lisinopril and bisoprolol for hypertension and has no allergies. On examination, the patient appears cachectic. He responds to stimulation but is lethargic and unable to provide any significant history. His blood pressure is 138/90 mm Hg, heart rate is 100/min, and his oxygen saturation on room air is 90%. His mucous membranes are moist, heart rate is regular without murmurs or an S3/S4 gallop, and his extremities are without any edema. His pulmonary examination shows mildly diminished breath sounds in the right lower lobe with bilateral wheezing. His laboratory values are shown: Sodium 110 mEq/L Potassium 4.1 mEq/L Chloride 102 mEq/L CO2 41 mm Hg BUN 18 Creatinine 1.3 mg/dL Glucose 93 mg/dL Urine osmolality 600 mOsm/kg H2O Plasma osmolality 229 mEq/L WBC 8,200 cells/mL Hgb 15.5 g/dL Arterial blood gas pH 7.36/pCO2 60/pO2 285 Chest X-ray demonstrates a mass in the right upper lobe. What is the most appropriate treatment to address the patient’s hyponatremia?

3% saline at 35 mL/h

step2&3

D

A 30-year-old male presents with a testicular mass of unknown duration. The patient states he first noticed something unusual with his right testicle two weeks ago, but states he did not think it was urgent because it was not painful and believed it would resolve on its own. It has not changed since he first noticed the mass, and the patient still denies pain. On exam, the patient’s right testicle is non-tender, and a firm mass is felt. There is a negative transillumination test, and the mass is non-reducible. Which of the following is the best next step in management?

Testicular ultrasound

step2&3

B

A 1-year-old boy is brought to the emergency department after his mother witnessed him swallow a nickel-sized battery a few hours ago. She denies any episodes of vomiting or hematemesis. The vital signs include: temperature 37.0°C (98.6°F), blood pressure 95/45 mm Hg, pulse 140/min, respiratory rate 15/min, and oxygen saturation 99% on room air. On physical examination, the patient is alert and responsive. The oropharynx is clear. The cardiac exam is significant for a grade 2/6 holosystolic murmur loudest at the left lower sternal border. The lungs are clear to auscultation. The abdomen is soft and nontender with no hepatosplenomegaly. Bowel sounds are present. What is the most appropriate next step in the management of this patient?

Immediate endoscopic removal

step2&3

E

A 28-year-old soldier is brought back to a military treatment facility 45 minutes after sustaining injuries in a building fire from a mortar attack. He was trapped inside the building for around 20 minutes. On arrival, he is confused and appears uncomfortable. He has a Glasgow Coma Score of 13. His pulse is 113/min, respirations are 18/min, and blood pressure is 108/70 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 96%. Examination shows multiple second-degree burns over the chest and bilateral upper extremities and third-degree burns over the face. There are black sediments seen within the nose and mouth. The lungs are clear to auscultation. Cardiac examination shows no abnormalities. The abdomen is soft and nontender. Intravenous fluid resuscitation is begun. Which of the following is the most appropriate next step in management?

Intubation and mechanical ventilation

step2&3

C

A 49-year-old woman presents to her primary care physician for a routine health maintenance examination. She says that she is currently feeling well and has not noticed any acute changes in her health. She exercises 3 times a week and has tried to increase the amount of fruits and vegetables in her diet. She has smoked approximately 1 pack of cigarettes every 2 days for the last 20 years. Her last pap smear was performed 2 years ago, which was unremarkable. Her past medical history includes hypertension and type II diabetes. Her mother was diagnosed with breast cancer at 62 years of age. The patient is 5 ft 5 in (165.1 cm), weighs 185 lbs (84 kg), and has a BMI of 30.8 kg/m^2. Her blood pressure is 155/98 mmHg, pulse is 90/min, and respirations are 18/min. Physical examination is unremarkable. Lipid studies demonstrate an LDL cholesterol of 130 mg/dL and an HDL cholesterol of 42 mg/dL. Which of the following is the best next step in management?

Statin therapy

step2&3

E

A 24-year-old woman with a past medical history of anorexia nervosa presents to the clinic due to heavy menses, bleeding gums, and easy bruisability. She says she is trying to lose weight by restricting her food intake. She has taken multiple courses of antibiotics for recurrent sinusitis over the past month. No other past medical history or current medications. She is not sexually active. Her vital signs are as follows: temperature 37.0°C (98.6°F), blood pressure 90/60 mm Hg, heart rate 100/min, respiratory rate 16/min. Her BMI is 16 kg/m2. Her physical examination is significant for ecchymosis on the extremities, dry mucous membranes, and bleeding gums. A gynecological exam is non-contributory. Laboratory tests show a prolonged PT, normal PTT, and normal bleeding time. CBC shows microcytic anemia, normal platelets, and normal WBC. Her urine pregnancy test is negative. Which of the following is the most likely cause of her condition?

Vitamin K deficiency

step2&3

A

A 65-year-old obese female presents to the emergency room complaining of severe abdominal pain. She reports pain localized to the epigastrium that radiates to the right scapula. The pain occurred suddenly after a fast food meal with her grandchildren. Her temperature is 100.9°F (38.2°C), blood pressure is 140/85 mmHg, pulse is 108/min, and respirations are 20/min. On examination, she demonstrates tenderness to palpation in the epigastrium. She experiences inspiratory arrest during deep palpation of the right upper quadrant but this exam finding is not present on the left upper quadrant. A blockage at which of the following locations is most likely causing this patient’s symptoms?

Cystic duct

step1

C

A 27-year-old Asian woman presents to her primary care physician with joint pain and a headache. She has had intermittent joint and muscle pain for the past several months in the setting of a chronic headache. She states that the pain seems to migrate from joint to joint, and her muscles typically ache making it hard for her to sleep. The patient's past medical history is non-contributory, and she is currently taking ibuprofen for joint pain. Physical exam is notable for an asymmetrical pulse in the upper extremities. The patient has lost 10 pounds since her previous visit 2 months ago. Laboratory values are notable for an elevated C-reactive protein and erythrocyte sedimentation rate. Which of the following is the best next step in management?

Prednisone

step2&3

C

Your colleague has been reading the literature on beta-carotene supplementation and the risk of heart disease. She thinks they may share a clinically relevant association and would like to submit an editorial to a top journal. Upon final literature review, she discovers a newly published study that refutes any association between beta-carotene and heart disease. Your colleague is upset; you suggest that she, instead, mathematically pool the results from all of the studies on this topic and publish the findings. What type of study design are you recommending to your colleague?

Meta-analysis

step1

D

A 15-year-old girl comes to the physician with her father for evaluation of short stature. She feels well overall but is concerned because all of her friends are taller than her. Her birth weight was normal. Menarche has not yet occurred. Her father says he also had short stature and late puberty. The girl is at the 5th percentile for height and 35th percentile for weight. Breast development is Tanner stage 2. Pubic and axillary hair is absent. An x-ray of the left hand and wrist shows a bone age of 12 years. Further evaluation of this patient is most likely to show which of the following sets of laboratory findings? $$$ FSH %%% LH %%% Estrogen %%% GnRH $$$

Normal normal normal normal

step1

C

In which of the following pathological states would the oxygen content of the trachea resemble the oxygen content in the affected alveoli?

Pulmonary embolism

step1

C

A previously healthy 32-year-old man comes to the physician because of a 1-week history of upper back pain, dyspnea, and a sensation of pressure in his chest. He has had no shortness of breath, palpitations, fevers, or chills. He emigrated from Ecuador when he was 5 years old. He does not smoke or drink alcohol. He takes no medications. He is 194 cm (6 ft 4 in) tall and weighs 70.3 kg (155 lb); BMI is 19 kg/m2. His temperature is 37.2°C (99.0°F), pulse is 73/min, respirations are 15/min, and blood pressure is 152/86 mm Hg in the right arm and 130/72 mg Hg in the left arm. Pulmonary examination shows faint inspiratory wheezing bilaterally. A CT scan of the chest with contrast is shown. Which of the following is the most likely underlying cause of this patient's condition?

Cystic medial necrosis

step2&3

B

A 26-year-old woman presents to the emergency department with fever, chills, lower quadrant abdominal pain, and urinary frequency for the past week. Her vital signs include temperature 38.9°C (102.0°F), pulse 110/min, respirations 16/min, and blood pressure 122/78 mm Hg. Physical examination is unremarkable. Urinalysis reveals polymorphonuclear leukocytes (PMNs) > 10 cells/HPF and the presence of bacteria (> 105 CFU/mL). Which of the following is correct concerning the most likely microorganism responsible for this patient’s condition?

Gram-negative rod-shaped bacilli

step1

C

A 30-year-old man comes to the emergency department because of the sudden onset of back pain beginning 2 hours ago. Beginning yesterday, he noticed that his eyes started appearing yellowish and his urine was darker than normal. Two months ago, he returned from a trip to Greece, where he lived before immigrating to the US 10 years ago. Three days ago, he was diagnosed with latent tuberculosis and started on isoniazid. He has worked as a plumber the last 5 years. His temperature is 37.4°C (99.3°F), pulse is 80/min, and blood pressure is 110/70 mm Hg. Examination shows back tenderness and scleral icterus. Laboratory studies show: Hematocrit 29% Leukocyte count 8000/mm3 Platelet count 280,000/mm3 Serum Bilirubin Total 4 mg/dL Direct 0.7 mg/dL Haptoglobin 15 mg/dL (N=41–165 mg/dL) Lactate dehydrogenase 180 U/L Urine Blood 3+ Protein 1+ RBC 2–3/hpf WBC 2–3/hpf Which of the following is the most likely underlying cause of this patient's anemia?"

Absence of reduced glutathione

step2&3

B

A 69-year-old Caucasian man presents for a routine health maintenance examination. He feels well. He has no significant past medical history. He takes aspirin for the occasional headaches that he has had for over several years. He exercises every day and does not smoke. His father was diagnosed with a hematologic malignancy at 79 years old. The patient’s vital signs are within normal limits. Physical examination shows no abnormalities. The laboratory test results are as follows: Hemoglobin 14.5 g/dL Leukocyte count 62,000/mm3 Platelet count 350,000/mm3 A peripheral blood smear is obtained (shown on the image). Which of the following best explains these findings?

Chronic lymphocytic leukemia

step2&3

D

A 62-year-old woman is referred to a tertiary care hospital with a history of diplopia and fatigue for the past 3 months. She has also noticed difficulty in climbing the stairs and combing her hair. She confirms a history of 2.3 kg (5.0 lb) weight loss in the past 6 weeks and constipation. Past medical history is significant for type 2 diabetes mellitus. She has a 50-pack-year cigarette smoking history. Physical examination reveals a blood pressure of 135/78 mm Hg supine and 112/65 while standing, a heart rate of 82/min supine and 81/min while standing, and a temperature of 37.0°C (98.6°F). She is oriented to time and space. Her right upper eyelid is slightly drooped. She has difficulty in abducting the right eye. Pupils are bilaterally equal and reactive to light with accommodation. The corneal reflex is intact. Muscle strength is reduced in the proximal muscles of all 4 limbs, and the lower limbs are affected more when compared to the upper limbs. Deep tendon reflexes are bilaterally absent. After 10 minutes of cycling, the reflexes become positive. Sensory examination is normal. Diffuse wheezes are heard on chest auscultation. Which of the following findings is expected?

Incremental pattern on repetitive nerve conduction studies

step2&3

C

A 60-year-old man is brought to the emergency department by police officers because he was acting strangely in public. The patient was found talking nonsensically to characters on cereal boxes in the store. Past medical history is significant for multiple hospitalizations for alcohol-related injuries and seizures. The patient’s vital signs are within normal limits. Physical examination shows a disheveled male who is oriented to person, but not time or place. Neurologic examination shows nystagmus and severe gait ataxia. A T1/T2 MRI is performed and demonstrates evidence of damage to the mammillary bodies. The patient is given the appropriate treatment for recovering most of his cognitive functions. However, significant short-term memory deficits persist. The patient remembers events from his past such as the school and college he attended, his current job, and the names of family members quite well. Which of the following is the most likely diagnosis in this patient?

Korsakoff's syndrome

step1

C

A 43-year-old woman presents to her primary care physician for a general wellness appointment. The patient states that sometimes she has headaches and is ashamed of her body habitus. Otherwise, the patient has no complaints. The patient's 90-year-old mother recently died of breast cancer. The patient smokes 1 pack of cigarettes per day. She drinks 2-3 glasses of red wine per day with dinner. She has been considering having a child as she has just been promoted to a position that gives her more time off and a greater income. The patient's current medications include lisinopril, metformin, and a progesterone intrauterine device (IUD). On physical exam, you note a normal S1 and S2 heart sound. Pulmonary exam is clear to auscultation bilaterally. The patient's abdominal, musculoskeletal, and neurological exams are within normal limits. The patient is concerned about her risk for breast cancer and asks what she can do to reduce her chance of getting this disease. Which of the following is the best recommendation for this patient?

Exercise and reduce alcohol intake

step2&3

E

A 12-year-old boy is brought to his pediatrician with a high fever. He was feeling fatigued yesterday and then developed a high fever overnight that was accompanied by chills and malaise. This morning he also started complaining of headaches and myalgias. He has otherwise been healthy and does not take any medications. He says that his friends came down with the same symptoms last week. He is given oseltamivir and given instructions to rest and stay hydrated. He is also told that this year the disease is particularly infectious and is currently causing a global pandemic. He asks the physician why the same virus can infect people who have already had the disease and is told about a particular property of this virus. Which of the following properties is required for the viral genetic change that permits global pandemics of this virus?

Segmented genomic material

step1

E

A 52-year-old woman presents to the clinic with complaints of intermittent chest pain for 3 days. The pain is retrosternal, 3/10, and positional (laying down seems to make it worse). She describes it as “squeezing and burning” in quality, is worse after food intake and emotional stress, and improves with antacids. The patient recently traveled for 4 hours in a car. Past medical history is significant for osteoarthritis, hypertension and type 2 diabetes mellitus, both of which are moderately controlled. Medications include ibuprofen, lisinopril, and hydrochlorothiazide. She denies palpitations, dyspnea, shortness of breath, weight loss, fever, melena, or hematochezia. What is the most likely explanation for this patient’s symptoms?

Incompetence of the lower esophageal sphincter

step1

C

A 24-year-old man presents to the emergency department for severe abdominal pain for the past day. The patient states he has had profuse, watery diarrhea and abdominal pain that is keeping him up at night. The patient also claims that he sees blood on the toilet paper when he wipes and endorses having lost 5 pounds recently. The patient's past medical history is notable for IV drug abuse and a recent hospitalization for sepsis. His temperature is 99.5°F (37.5°C), blood pressure is 120/68 mmHg, pulse is 100/min, respirations are 14/min, and oxygen saturation is 98% on room air. On physical exam, you note a young man clutching his abdomen in pain. Abdominal exam demonstrates hyperactive bowel sounds and diffuse abdominal tenderness. Cardiopulmonary exam is within normal limits. Which of the following is the next best step in management?

Vancomycin

step2&3

B

A 57-year-old man is brought to the emergency department for worsening pain and swelling of his left ankle for the past 2 hours. The pain is severe and awakened him from sleep. He has hypertension and hyperlipidemia. Current medications include hydrochlorothiazide and pravastatin. His temperature is 37.8°C (100.1°F), pulse is 105/min, and blood pressure is 148/96 mm Hg. Examination shows exquisite tenderness, erythema, and edema of the left ankle; active and passive range of motion is limited by pain. Arthrocentesis of the ankle joint yields cloudy fluid with a leukocyte count of 19,500/mm3 (80% segmented neutrophils). Gram stain is negative. A photomicrograph of the joint fluid aspirate under polarized light is shown. Which of the following is the most appropriate pharmacotherapy?

Colchicine

step2&3

D

A 37-year-old man presents to the physician because of dysphagia and regurgitation for the past 5 years. In recent weeks, it has become very difficult for him to ingest solid or liquid food. He has lost 3 kg (6 lb) during this time. He was admitted to the hospital last year because of pneumonia. Three years ago, he had an endoscopic procedure which partially improved his dysphagia. He takes amlodipine and nitroglycerine before meals. His vital signs are within normal limits. BMI is 19 kg/m2. Physical examination shows no abnormalities. A barium swallow X-ray is shown. Which of the following patterns of esophageal involvement is the most likely cause of this patient’s condition?

Absent peristalsis and impaired lower esophageal sphincter relaxation

step2&3

B

A 23-year-old woman is seen by her primary care physician. The patient has a several year history of excessive daytime sleepiness. She also reports episodes where she suddenly falls to the floor after her knees become weak, often during a laughing spell. She has no other significant past medical history. Her primary care physician refers her for a sleep study, which confirms the suspected diagnosis. Which of the following laboratory findings would also be expected in this patient?

Undetectable CSF hypocretin-1

step1

C

A 30-year-old woman comes to the physician with her husband because they have been trying to conceive for 15 months with no success. They have been sexually active at least twice a week. The husband sometimes has difficulties maintaining erection during sexual activity. During attempted vaginal penetration, the patient has discomfort and her pelvic floor muscles tighten up. Three years ago, the patient was diagnosed with body dysmorphic disorder. There is no family history of serious illness. She does not smoke or drink alcohol. She takes no medications. Vital signs are within normal limits. Pelvic examination shows normal appearing vulva without redness; there is no vaginal discharge. An initial attempt at speculum examination is aborted after the patient's pelvic floor muscles tense up and she experiences discomfort. Which of the following is the most likely diagnosis?

Genitopelvic pain disorder

step2&3

D

An otherwise healthy 76-year-old man is brought to the physician because of poor sleep for the past several years. Every night he has been sleeping less and taking longer to fall asleep. During the day, he feels tired and has low energy and difficulty concentrating. Sleep hygiene and relaxation techniques have failed to improve his sleep. He would like to start a short-term pharmacological therapy trial but does not want a drug that makes him drowsy during the day. Which of the following is the most appropriate pharmacotherapy for this patient?

Zaleplon

step1

D

A 23-year-old man is brought to the emergency department by ambulance following a motor vehicle accident. He was pinned between 2 cars for several hours. The patient has a history of asthma. He uses an albuterol inhaler intermittently. The patient was not the driver, and admits to having a few beers at a party prior to the accident. His vitals in the ambulance are stable. Upon presentation to the emergency department, the patient is immediately brought to the operating room for evaluation and surgical intervention. It is determined that the patient’s right leg has a Gustilo IIIC injury in the mid-shaft of the tibia with a severely comminuted fracture. The patient’s left leg suffered a similar injury but with damage to the peroneal nerve. The anesthesiologist begins to induce anesthesia. Which of the following agents would be contraindicated in this patient?

Succinylcholine

step2&3

E

A 3-year-old girl is brought to the physician for a well-child visit. Her father is concerned about the color and strength of her teeth. He says that most of her teeth have had stains since the time that they erupted. She also has a limp when she walks. Examination shows brownish-gray discoloration of the teeth. She has lower limb length discrepancy; her left knee-to-ankle length is 4 cm shorter than the right. Which of the following drugs is most likely to have been taken by this child's mother when she was pregnant?

Tetracycline

step1

E

A 2300-g (5.07-lb) male newborn is delivered at term to a 39-year-old woman. Examination shows a sloping forehead, a flat nasal bridge, increased interocular distance, low-set ears, a protruding tongue, a single palmar crease and an increased gap between the first and second toe. There are small white and brown spots in the periphery of both irises. The abdomen is distended. An x-ray of the abdomen shows two large air-filled spaces in the upper quadrant. This patient's condition is most likely associated with which of the following cardiac anomalies?

Atrioventricular septal defect

step1

C

A 47-year-old woman comes to the physician because of a 3-week history of generalized fatigue, mild fever, abdominal pain, and nausea. She attended the state fair over a month ago, where she tried a number of regional foods, and wonders if it might have been caused by something she ate. She has also noticed darkening of her urine, which she attributes to not drinking enough water recently. She has type 2 diabetes mellitus. She drinks 1–2 beers daily. She works as nursing assistant in a rehabilitation facility. Current medications include glyburide, sitagliptin, and a multivitamin. She appears tired. Her temperature is 38.1°C (100.6°F), pulse is 99/min, and blood pressure is 110/74 mm Hg. Examination shows mild scleral icterus. The liver is palpated 2–3 cm below the right costal margin and is tender. Laboratory studies show: Hemoglobin 10.6 g/dL Leukocyte count 11600/mm3 Platelet count 221,000/mm3 Serum Urea nitrogen 26 mg/dL Glucose 122 mg/dL Creatinine 1.3 mg/dL Bilirubin 3.6 mg/dL Total 3.6 mg/dL Direct 2.4 mg/dL Alkaline phosphatase 72 U/L AST 488 U/L ALT 798 U/L Hepatitis A IgG antibody (HAV-IgG) positive Hepatitis B surface antigen (HBsAg) positive Hepatitis B core IgG antibody (anti-HBc) positive Hepatitis B envelope antigen (HBeAg) positive Hepatitis C antibody (anti-HCV) negative Which of the following is the most likely diagnosis?"

Active chronic hepatitis B infection

step2&3

C

A 5-year-old boy is brought to the emergency department for evaluation of a progressive rash that started 2 days ago. The rash began on the face and progressed to the trunk and extremities. Over the past week, he has had a runny nose, a cough, and red, crusty eyes. He immigrated with his family from Turkey 3 months ago. His father and his older brother have Behcet disease. Immunization records are unavailable. The patient appears irritable and cries during the examination. His temperature is 40.0°C (104°F). Examination shows general lymphadenopathy and dry mucous membranes. Skin turgor is decreased. There is a blanching, partially confluent erythematous maculopapular exanthema. Examination of the oral cavity shows two 5-mm aphthous ulcers at the base of the tongue. His hemoglobin concentration is 11.5 g/dL, leukocyte count is 6,000/mm3, and platelet count is 215,000/mm3. Serology confirms the diagnosis. Which of the following is the most appropriate next step in management?

Vitamin A supplementation

step2&3

C

A 7-year-old boy presents to the ER with progressive dysphagia over the course of 3 months and a new onset fever for the past 24 hours. The temperature in the ER was 39.5°C (103.1°F). There are white exudates present on enlarged tonsils (Grade 2). Routine blood work reveals a WBC count of 89,000/mm3, with the automatic differential yielding a high (> 90%) percentage of lymphocytes. A peripheral blood smear is ordered, demonstrating the findings in the accompanying image. The peripheral smear is submitted to pathology for review. After initial assessment, the following results are found on cytologic assessment of the cells: TdT: positive CALLA (CD 10): positive Which of the following cell markers are most likely to be positive as well?

CD 19

step1

D

A 74-year-old man presents to the emergency department with sudden onset of abdominal pain that is most felt around the umbilicus. The pain began 16 hours ago and has no association with meals. He has not been vomiting, but he has had several episodes of bloody loose bowel movements. He was hospitalized 1 week ago for an acute myocardial infarction. He has had diabetes mellitus for 35 years and hypertension for 20 years. He has smoked 15–20 cigarettes per day for the past 40 years. His temperature is 36.9°C (98.4°F), blood pressure is 95/65 mm Hg, and pulse is 95/min. On physical examination, the patient is in severe pain, there is a mild periumbilical tenderness, and a bruit is heard over the epigastric area. Which of the following is the most likely diagnosis?

Acute mesenteric ischemia

step2&3

C

A 33-year-old woman, gravida 2, para 1, at 26 weeks' gestation comes to the emergency department because of frequent contractions. The contractions are 40 seconds each, occurring every 2 minutes, and increasing in intensity. Her first child was delivered by lower segment transverse cesarean section because of a nonreassuring fetal heart rate. Her current medications include folic acid and a multivitamin. Her temperature is 36.9°C (98.4°F), heart rate is 88/min, and blood pressure is 126/76 mm Hg. Contractions are felt on the abdomen. There is clear fluid in the vulva and the introitus. The cervix is dilated to 5 cm, 70% effaced, and station of the head is -2. A fetal ultrasound shows polyhydramnios, a median cleft lip, and fused thalami. The corpus callosum, 3rd ventricle, and lateral ventricles are absent. The spine shows no abnormalities and there is a four chamber heart. Which of the following is the most appropriate next step in management?

Allow vaginal delivery

step2&3

B