NBME 32 – Block 1

A 10-year-old boy is unable to be awakened by his mother in the morning. He has a 3-year history of type 1 diabetes mellitus and receives frequent injections of insulin daily. His blood glucose concentration measured by glucometer is 25 mg/dL. His mother has been instructed to administer glucagon in this situation. Following subcutaneous administration of the drug, he awakens and his blood glucose concentration increases to 180 mg/dL. As a result of this treatment, which of the following enzymes was most likely converted to its inactive form in this patient?

A 1-week-old boy is admitted to the hospital because of an 8-hour history of vomiting and lethargy. He is at the 10th percentile for length, weight, and head circumference. His respirations are 40/min; other vital signs are within normal limits. Physical examination shows mild central cyanosis. There is no evidence of infection. His serum total calcium concentration is 7 mg/dL (N=8.8–10.8). Echocardiography shows defects consistent with tetralogy of Fallot. Array comparative genomic hybridization shows an autosomal deletion. This patient’s clinical phenotype is best explained by which of the following embryologic mechanisms?

An investigator is conducting a study of the epidemiology of hepatocellular carcinoma in the USA over the past 25 years. An increased incidence of this disease with viral infection is found. Which of the following viruses is most likely to be identified in this study?

Investigators are studying the relationship between dietary salt consumption and blood pressure in two populations, Population A and Population B. Data analysis yields the graphs shown. Which of the following is the most appropriate conclusion when comparing the correlation coefficients for dietary salt consumption and blood pressure between these two populations?

A 74-year-old man is admitted to the hospital because of a 6-week history of splenomegaly. The patient also has had fatigue for 15 weeks. Laboratory studies show:

Cells were not obtained during an effort to aspirate the bone marrow. Flow cytometry of peripheral blood shows a population of cells to be CD20+ and CD103+. Which of the following is the most likely diagnosis?

A 79-year-old woman is brought to the physician because of two episodes of impaired vision of the right eye during the past 5 days. She experienced dimming in this eye after it seemed as if a curtain or shade had come down over the eye. Each episode lasted for less than 1 minute and then resolved spontaneously. She has hypertension and hyperlipidemia treated with atenolol and simvastatin. Her blood pressure is 138/96 mm Hg. Ophthalmologic examination of both eyes shows arteriolar narrowing. Cardiovascular and neurologic examinations show no abnormalities. The most likely cause of her condition is stenosis of which of the following arteries?

A 52-year-old man is brought to the physician by his wife because of a 6-month history of cough productive of yellow-green, foul-smelling, purulent sputum. He has a history of recurrent severe pneumonia since the age of 16 years. Rhonchi are present in both lungs, but they are heard loudest in the left lower lobe. The airways contain thick, obstructing mucus. Which of the following is the most likely diagnosis?

A 19-year-old woman is brought to the emergency department because of a 1-day history of high-grade fever; dizziness; and a diffuse, red, sunburn-like rash. Two days earlier, she underwent rhinoplasty to repair a deviated septum and her right naris was packed because of bleeding. Her temperature is 39.5°C (103°F), and blood pressure is 80/50 mm Hg. Culture of a smear obtained from the nares grows coagulase-positive, gram-positive cocci. The toxin responsible for this patient’s signs and symptoms induces the production of large amounts of cytokines through which of the following mechanisms?

A 46-year-old man comes to the emergency department because of a 2-day history of fever, sore throat, and pain with swallowing. He recently emigrated from Russia and has no history of major medical illness. His temperature is 38.4°C (101.1°F), pulse is 90/min, respirations are 19/min, and blood pressure is 120/85 mm Hg. Physical examination shows a markedly swollen neck, enlarged cervical lymph nodes, and a grayish coating on the tonsils. Culture of tracheal aspirate grows a gram-positive bacillus. The patient is admitted to the hospital. Six days later, his respiratory function quickly deteriorates, and, despite appropriate intervention, he dies. At autopsy, a structure is removed from the surface of the trachea and proximal mainstem bronchi; the structure is shown in the photograph. Which of the following organs in this patient was most likely also affected by the infectious agent?

A 35-year-old man comes to the physician because of pain and swelling of his right arm where he scraped it on a tree branch 2 days ago. His temperature is 38.3°C (101°F). Examination of the right forearm shows edema around a fluctuant erythematous lesion at the site of trauma. The area is extremely tender to palpation. Which of the following mediators of acute inflammation had the greatest role in producing the pain in this patient’s arm?

A sedentary 28-year-old man with recently diagnosed hypertension comes to the physician for a follow-up examination. His last three blood pressure readings averaged 145/85 mm Hg. He lives with two other men who do not like to cook. Their usual diet consists of pizza, fried chicken, or hamburgers for dinner. He typically has a salami sandwich for lunch. He has no family history of hypertension or cardiac disease. Which of the following is the most appropriate next step by the physician?

A 46-year-old man comes to the physician because of a 6-week history of generalized malaise and shivering; he also has had a 5-kg (11-lb) weight gain during this period. He tells the physician that he has been trying to eat healthy foods and has been consuming large amounts of seaweed lately. Physical examination shows an enlarged thyroid gland. His serum thyroid-stimulating hormone concentration is increased. The physician recommends that the patient decrease his seaweed intake, and the patient’s symptoms improve 2 weeks later. Which of the following effects of iodine best explains this patient’s original symptoms?

A 56-year-old man who is a colonel in the US Air Force and stationed at a missile silo in North Dakota comes to the clinic because of a 2-day history of severe back pain that began while he was shoveling snow. He rates the pain as 7 on a 10-point scale. The pain radiates to the back of his right thigh and calf. He spent the past 2 days on the couch because of the pain. There has been no weakness, fevers, weight loss, or change in bowel or bladder function during this period. He has a 10-year history of intermittent low back pain. Rest and ibuprofen therapy previously resulted in relief but has been ineffective during this time. He has no other history of major medical illness and takes no other medications. He appears to be in pain but can walk without assistance. He is 178 cm (5 ft 10 in) tall and weighs 95 kg (210 lb); BMI is 30 kg/m2. Pulse is 110/min; other vital signs are within normal limits. Physical examination shows paraspinal tenderness to palpation adjacent to the lumbar spine. Ankle jerk reflex is absent on the right. Sensation to pinprick is mildly decreased over the bottom of the right foot. Additional neurologic testing is most likely to show a deficit in which of the following?

A 16-year-old boy is brought to the emergency department because of a 3-day history of diarrhea and mild abdominal bloating. He has six to eight large, brown, nonbloody, foul-smelling, watery stools daily. He has not had fever, nausea, vomiting, abdominal pain, or blood in his stools. Six days ago, he returned from a 2-week camping trip with his family in the Ozark Mountains of southern Missouri. During the trip, they cooked and ate food they brought with them, and drank filtered water from streams. His vital signs are within normal limits. Physical examination shows no abnormalities. Test of the stool for occult blood is negative. Microscopic examination of a stool specimen shows binucleated trophozoites. The most appropriate first-line pharmacotherapy for this patient is a drug with which of the following mechanisms of action?

A 65-year-old man with a history of chronic myeloid leukemia comes to the physician because of a 3-day history of fever, abdominal pain, and diarrhea. Three months ago, he received a bone marrow transplant. His temperature is 38°C (100.4°F). Physical examination shows an erythematous maculopapular rash. A photomicrograph of a small-intestine biopsy specimen is shown. Which of the following mechanisms best explains the process shown?

A 35-year-old man comes to the office for a follow-up examination. Six months ago, he was diagnosed with hypertension, hyperlipidemia, major depressive disorder, and type 2 diabetes mellitus complicated by proteinuria. He had not seen a physician for 15 years before that visit. Medications are metformin, lisinopril, atorvastatin, and citalopram. He is 180 cm (5 ft 11 in) tall and weighs 118 kg (260 lb); BMI is 36 kg/m2. Temperature is 37.7°C (99.9°F), pulse is 86/min, respirations are 14/min, and blood pressure is 150/90 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 97%. Physical and mental status examinations disclose no abnormalities. Hemoglobin A1c is 9.2%. It is most appropriate to obtain additional history regarding which of the following at this time?

A 22-year-old woman who is unemployed comes to the physician because of a 3-month history of abdominal pain and constipation. She also has had abdominal bloating and cramping after eating small amounts of food. She says that she has a bowel movement only once weekly, even with the use of laxatives, and the bowel movements are formed and hard. She appears pale and is dressed in multiple layers. She is 168 cm (5 ft 6 in) tall and weighs 45 kg (100 lb); BMI is 16 kg/m2. Her temperature is 36.5°C (97.7°F), pulse is 55/min, respirations are 10/min, and blood pressure is 90/60 mm Hg. Physical examination shows a soft, nontender abdomen and hypoactive bowel sounds. The anterior superior iliac spines are prominent. Which of the following is the most likely cause of this patient’s symptoms?

A 72-year-old man comes to the emergency department because of a 1-hour history of substernal chest pain. He describes the pain as 10 on a 10-point scale. Coronary angiography shows a 90% occlusion of the left main coronary artery. He undergoes immediate coronary artery bypass grafting. He has hypertension and hypercholesterolemia. Results of preoperative laboratory studies are shown:

After a sternotomy, the medial aspect of the left 3rd rib fractures immediately when the left hemithorax is elevated to mobilize the left internal thoracic artery. A 4-cm mass is observed adjacent to the left internal thoracic artery, involving the inner aspect of the rib at the site of the fracture. Photomicrograph of a biopsy specimen of the mass is shown. Which of the following is the most likely diagnosis?

A 62-year-old man with cirrhosis comes to the physician because of a 1-week history of blood in his stool. Anoscopy shows several large internal hemorrhoids. Further evaluation shows portal hypertension. The most likely cause of the hemorrhoids in this patient is increased blood flow between which of the following portal and systemic venous structures?

A 32-year-old nulligravid woman is being evaluated for infertility for the past 2 years. Her menstrual periods occur every 24 to 26 days. An endometrial biopsy taken on cycle day 20 has a pathologic reading consistent with cycle day 14. Which of the following is the most likely diagnosis?

A 25-year-old man of Asian descent comes to the physician 1 week after an episode of facial flushing, severe headache, and profuse sweating after consuming 2 ounces of alcohol over a 60-minute period. Physical examination shows no abnormalities. An inherited decrease in the activity of which of the following hepatic enzymes is the most likely cause of this patient’s symptoms?

An 85-year-old woman dies of complications of dementia, Alzheimer type, and an autopsy is planned. During autopsy, the examiner wants to determine whether reactive astrogliosis occurred in the areas in or surrounding amyloid plaques in the brain. Immunohistochemistry will be used to quantify the presence of reactive astrocytes. The antibodies for this analysis will be chosen because of their ability to bind to which of the following proteins?

A 67-year-old man comes to the physician because of a 6-month history of progressive urinary frequency and urgency that often awaken him at night. Examination of the prostate shows a 3-cm, palpable hard mass. His serum prostate-specific antigen concentration is markedly increased. A prostate biopsy specimen shows adenocarcinoma. Which of the following structures is most susceptible to direct extension of this tumor?

A 23-year-old man comes to the physician to have an orthopaedic cast removed 6 weeks after he sustained a fracture to his right lower leg in a skateboarding accident. After removal of the cast, examination of the right lower extremity shows markedly decreased sensation to pinprick over the dorsum of the foot. An x-ray of the right lower extremity is shown; the X indicates the subcutaneous position of the injured nerve. This nerve most likely supplies which of the following muscles in this patient?

An 83-year-old woman is brought to the emergency department because of an 8-hour history of severe abdominal pain. She has a history of atrial fibrillation, cerebral infarction, coronary artery disease, and type 2 diabetes mellitus. She is not currently receiving anticoagulant therapy because of several recent falls. Her temperature is 38.4°C (101.1°F), pulse is 130/min, respirations are 18/min, and blood pressure is 90/50 mm Hg. Palpation of the abdomen elicits severe pain with rebound tenderness. Results of laboratory studies are shown:

An abdominal CT scan shows free air in the abdomen and a diffusely edematous colon. Which of the following is the most likely cause of the serum findings in this patient?

A 39-year-old woman who received her first chemotherapy session for breast cancer has nausea and vomiting in the elevator as she leaves the clinic. Two weeks later, she vomits as she steps off the elevator for her second chemotherapy appointment. Which of the following mechanisms is most likely to be involved?

A 63-year-old woman with a history of congestive heart failure comes to the physician because of a 1-day history of fever, headache, and nonproductive cough. Her temperature is 38.6°C (101.5°F), pulse is 94/min, respirations are 16/min, and blood pressure is 144/84 mm Hg. Physical examination shows no other abnormalities. Rapid antigen testing of a nasopharyngeal swab specimen is positive for influenza A virus. Treatment with oseltamivir is initiated. Which of the following viral processes is likely to be affected the most by this medication?

A 64-year-old man is brought to the emergency department by ambulance 30 minutes after he collapsed at home following the onset of a severe headache. A normal CT angiogram of the arteries at the base of the brain is shown; the arrow indicates the occluded vessel in this patient. Which of the following neurologic findings is most likely present in this patient?

A pilot study is conducted to determine if a low-fat diet is effective in promoting weight loss in six overweight patients who are seen at a clinic. The patients’ weights are measured at the time the diet is begun and 6 months later. Results are shown:

Which of the following statistical tests is the best method to determine if the diet is effective in promoting weight loss in these patients?

A 5-year-old boy is brought to the physician for evaluation of a possible immunodeficiency. He has a history of numerous episodes of otitis media and sinusitis, and two episodes of pneumonia. Today, his T-lymphocyte counts are within the reference ranges. Serologic studies show:

Type IV (delayed) hypersensitivity responses to mumps and diphtheria toxoid antigens are normal. In vitro lymphocyte proliferation studies with phytohemagglutinin show normal findings. A deficiency of which of the following best explains the immunologic abnormality in this patient?

A 23-year-old man is admitted to the hospital with community-acquired pneumonia. He is treated with azithromycin and ceftriaxone. Two days later, he becomes agitated and disoriented, and he also develops diarrhea. His friends say that the patient frequently abuses prescription medications, but they are not sure what he has been taking. Physical examination shows dilated pupils that are reactive to light and diaphoresis with piloerection. The most likely cause of these findings is withdrawal from which of the following drugs?

A 45-year-old man undergoes cardiac catheterization because of a 1-year history of chest pain with exertion. During the procedure, acetylcholine is infused into a coronary artery, and it causes vasoconstriction. The dysfunctional endothelial cells from this artery are more likely than normal endothelial cells to do which of the following?

A 45-year-old man with alcohol use disorder is admitted to the hospital for acute pancreatitis. He initially responds well to bed rest and intravenous fluid, but 1 week later he has persistent fever and epigastric pain. His temperature is 38.6°C (101.5°F). Abdominal examination shows a tender epigastric mass. Laboratory studies show a leukocyte count of 13,500/mm3 and serum amylase activity of 300 U/L. Which of the following is the most likely cause of these findings?

A 55-year-old postmenopausal woman comes to the physician because of two episodes of uterine bleeding, abdominal discomfort, and bilateral breast tenderness during the past 3 months. Physical examination shows a normal-sized uterus and a 10-cm mass in the left ovary. Which of the following neoplasms is most likely in this patient’s left ovary?

A previously healthy 11-year-old boy is brought to the physician by his mother because of a 3-month history of an itchy rash on the inside of his elbows and behind his knees. There is a family history of asthma and hay fever. His temperature is 37°C (98.6°F). Physical examination shows the rash depicted in the photograph shown. Which of the following is the most likely diagnosis?

A 3-year-old girl is brought to the emergency department by her parents 45 minutes after the patient inserted a peanut into her left nostril. The parents were unable to retrieve it. She has no history of serious illness and receives no medications. The patient appears healthy and is alert and crying. She is at the 50th percentile for height and weight. BMI is at the 50th percentile. Vital signs are within normal limits. Physical examination shows no abnormalities. Nasoscopic examination is most likely to show the object lodged in which of the following spaces in this patient?

A 35-year-old woman comes to the physician because of a 3-month history of heat intolerance, palpitations, anxiety, and shakiness of her hands. Her pulse is 100/min, respirations are 20/min, and blood pressure is 140/60 mm Hg. Physical examination shows hand tremor. Serum studies show a thyroid-stimulating hormone (TSH) concentration less than 0.1 μU/mL and thyroxine (T4) concentration of 20 μg/dL. Treatment with methimazole is begun. Her symptoms resolve within 3 weeks. Which of the following initial mechanisms of action best explains the timing of the resolution of this patient’s symptoms?

An investigator is studying the role of Bruton tyrosine kinase (BTK) in an immunodeficiency disorder. It is found that the function of BTK, which plays a primary role in the maturation of B lymphocytes from pro-B lymphocytes to pre-B lymphocytes, is abnormal in patients with this condition. Which of the following structures is most likely to have a normal number of lymphocytes in these patients?

A 24-year-old white woman is brought to the emergency department 90 minutes after the sudden onset of moderate chest pain and shortness of breath. She has no history of recent trauma, hospitalizations, or operative procedures. She was treated for deep venous thrombosis at the age of 20 years. She is in obvious discomfort. Her temperature is 37.6°C (99.7°F), pulse is 100/min, respirations are 30/min, and blood pressure is 140/100 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 88%. A diagnosis of pulmonary embolism is made. Which of the following hypercoagulable disorders is the most common predisposing risk factor for this condition in this patient?

A 25-year-old woman comes to the office to undergo genetic testing because of multiple instances of cancer in her family, illustrated in the pedigree shown. The patient is indicated by the arrow. The type of cancer and the age (in years) when the family member was diagnosed (dx) are also indicated. She has no history of serious illness and takes no medications. Vital signs are within normal limits. Physical examination shows no abnormalities. Which of the following genetic mechanisms best explains this patient’s risk for developing a type of cancer experienced by one of her family members?

During a 10-km (6-mile) race in hot (90°F) weather, a 35-year-old man is brought to the emergency department 30 minutes after he became disoriented and collapsed. His rectal temperature is 41°C (105.8°F), pulse is 130/min and weak, and blood pressure is 90/50 mm Hg. Physical examination shows hot dry skin. His condition gradually improves over the next 48 hours, but he remains oliguric during this period. This patient most likely has which of the following lesions in the kidneys at this time?

A 16-year-old boy comes to the physician because of a 2-month history of falling asleep during classes at school. He has no other concerns or stressors. He says that he recently began going to bed about midnight and getting up at 6 am in order to be at school in time for his first class that begins at 7:30 am. He maintains a B grade average and is a member of the chess club at his high school. He is 183 cm (6 ft) tall and weighs 79 kg (175 lb); BMI is 24 kg/m2. His vital signs are within normal limits. Physical examination shows no abnormalities. Which of the following is the most appropriate initial response by the physician?

A 56-year-old woman comes to the office because of a 2-week history of shortness of breath and nonproductive cough; the shortness of breath is more severe when she is lying down. She also has had a 5.5-kg (12-lb) weight loss during the past 3 months. She had breast cancer 12 years ago that was treated with chemotherapy and surgery. Her respirations are 20/min, and blood pressure is 90/60 mm Hg. Physical examination shows a jugular venous pressure of 15 cm H2O (N=5–8). The lungs are clear. Cardiac examination shows decreased heart sounds and a grade 1/6 systolic murmur that is heard throughout the precordium. Which of the following is the most likely cause of this patient’s condition?

A previously healthy 18-year-old woman is brought to the emergency department because of drowsiness for 6 hours. Two days ago, she took an overdose of acetaminophen following an argument with her boyfriend. Her pulse is 100/min, and blood pressure is 90/60 mm Hg. Physical examination shows jaundice and a soft abdomen with tenderness of the right upper quadrant. During the examination, she has a generalized tonic-clonic seizure. Her blood glucose concentration is 40 mg/dL. Which of the following is the most likely underlying cause of the laboratory findings in this patient?

A 24-year-old woman comes to the emergency department because of a 1-day history of fever, chills, headache, and severe malaise. Two days ago, she returned from a 3-week mission trip to Kenya. While she was in Kenya, she took chloroquine, which was given to her by a friend, for antimalarial prophylaxis and drank only bottled water. Current medications also include an oral contraceptive. Her temperature is 38.2°C (100.8°F), pulse is 84/min, respirations are 14/min, and blood pressure is 110/70 mm Hg. Physical examination shows pallor. A photomicrograph of a peripheral blood smear is shown. Which of the following best explains this patient’s apparent acquisition of this infection?

A 20-year-old woman is brought to the emergency department because of a 1-week history of temperatures greater than 39°C (102.2°F), shortness of breath, severe chest pain, and a persistent cough. Her temperature now is 38.9°C (102°F), and respirations are 22/min. Pulse oximetry on room air shows an oxygen saturation of 84%. Physical examination shows mild cyanosis of the lips and nail beds. Chest x-rays show consolidation of the right lower lobe of the lung. A sputum culture grows Streptococcus pneumoniae. Which of the following is the most likely cause of the cyanosis in this patient?

A 56-year-old man comes to the physician for a follow-up examination after he had blood pressure readings of 162/98 mm Hg and 174/100 mm Hg during a 2-week period. His pulse is 84/min, and blood pressure now is 172/96 mm Hg. Physical examination shows no other abnormalities. His serum creatinine concentration is 0.9 mg/dL. An ECG shows no abnormalities. A diagnosis of hypertension is made, and enalapril and a low-sodium diet are prescribed. Two weeks later, his blood pressure is 128/82 mm Hg, and serum creatinine concentration is 3.2 mg/dL. Which of the following is the most likely cause of this patient’s hypertension?

A previously healthy 49-year-old man comes to the emergency department because of a 4-hour history of severe, cramping, flank pain. The pain is intense, and he describes it as “coming in waves.” He is 168 cm (5 ft 6 in) tall and weighs 64 kg (142 lb); BMI is 23 kg/m2. Physical examination shows marked right flank tenderness. Two hours later, the pain migrates down the pelvis, and he passes a renal calculus. His serum calcium concentration is 11.5 mg/dL, and his serum phosphorus concentration is 1.8 mg/dL. Urinalysis shows blood. After discussing the diagnosis with the patient, it is most appropriate for the physician to state which of the following?

A 37-year-old woman returns to the physician’s office after having been evaluated for a breast lump that is malignant and has metastasized widely. Which of the following is the most appropriate action immediately after informing the patient of the diagnosis?

A 10-year-old girl is brought to the office by her father because of a 2-week history of a rash on her face, eyelids, and the knuckles of both hands. She also has had generalized muscle pain and weakness during this period that has made it difficult for her to keep her arms elevated while brushing her hair and getting in and out of the car. She has fallen twice but has not sustained any injuries. She has no history of serious illness and receives no medications. Her 15-year-old sister has no history of serious illness. The patient’s temperature is 37.2°C (99.0°F), pulse is 68/min, respirations are 14/min, and blood pressure is 105/65 mm Hg. Photographs of the patient’s left eyelid and right hand are shown. Periorbital edema is noted bilaterally. Erythrocyte sedimentation rate is 20 mm/h. If a muscle biopsy specimen were obtained in this patient, it would most likely show which of the following findings?