NBME Practice Questions

A 67-year-old woman is hospitalized because of abdominal pain and persistent copious

vomiting for 24 hours. Two weeks ago, she was hospitalized for treatment of atrial

fibrillation; after cardioversion to a normal sinus rhythm, she began treatment with

warfarin. Yesterday, at a follow-up visit, her INR was 6 (?? normal), and her medication

was discontinued. She takes no other medications. Her temperature is 37°C (98.6°F),

pulse is 120/min and regular, respirations are 20/min, and blood pressure is 100/78 mm

Hg. The abdomen is distended and moderately tender; there is voluntary guarding in the

epigastrium (??? source of pain) There are no masses, organomegaly, or obvious

hernias. Rectal examination shows no abnormalities. Test of the stool for occult blood is

negative. Her hemoglobin concentration has decreased from 13 g/dL yesterday to 7.8

g/dL today. An ECG shows a normal sinus rhythm. Which of the following is the most

likely explanation for this patient's abdominal symptoms? - Intramural hematoma of the

proximal small bowel

A 4-year-old boy is brought to the physician by his parents because of fatigue and

irritability over the past 2 months. The family visited relatives in rural Louisiana 5 months

ago where the patient ran around barefoot. The child is active and appears normal. The

conjunctivae are pale. Laboratory studies include a normal leukocyte count with 15%

eosinophils. A stool preparation discloses the parasite egg shown. Which of the

following is the most likely cause of fatigue and irritability in this patient? - Microcytic

anemia

Two days after beginning primaquine for malaria prophylaxis, a 17-year-old African

American boy is brought to the physician because of dark urine and yellowing of his

eyes. His pulse is 88/min, respirations are 12/min, and blood pressure is 124/68 mm

Hg. Examination shows scleral icterus and pale mucous membranes. His hemoglobin

concentration is 10 g/dL. A blood smear shows erythrocyte fragments and Heinz bodies.

Which of the following is the most likely explanation for these findings? - Deficiency of

glucose 6-phosphate dehydrogenase

A one-day-old newborn male is found to have hemolytic disease of the newborn. Both

parents are Rh-positive, mother is positive for IgG isohemagglutinins, while father is

negative. Which of the following parental blood types most likely caused this condition?

- Mother: O and Father: AB

One week after receiving 4 units of packed red blood cells for acute hemorrhage due to

a gunshot wound, a 17-year-old male develops fatigue, jaundice. Laboratory results

show the following:Hemoglobin 8.8 g/dL Hematocrit 28%, Serum total bilirubin 5 mg/dL

Serum lactate dehydrogenase 120 U/L. Liver and kidney function tests are otherwise

within normal limits. Which of the following is the most appropriate next step in

diagnosis? - Direct and indirect antiglobulin (Coombs) tests

A 6-month-old boy is brought to the physician because of left knee swelling for 24

hours. Three months ago, he had three large hematomas on his forehead that resolved

without treatment (??). His two sisters and his mother have no history of similar

symptoms. His mother's maternal uncle and her brother died (x-linked recessive) before

the age of 30 years of massive cerebral hemorrhages. Physical examination shows

deep ecchymosis over the buttocks and severe swelling of the left knee. The most likely

explanation for these findings is a deficiency of which of the following? - Factor VIII

(antihemophilic factor)

Three days after undergoing elective laparoscopic cholecystectomy for cholelithiasis, a

42-year-old woman has the onset of hematomas at all surgical sites. She was treated

for deep venous thrombosis 3 years ago but was not taking any medications at the time

of this admission. Results of preoperative laboratory studies were within the reference

range. Prior to the operation, she received heparin and underwent application of

compression stockings. Her initial postoperative course was uncomplicated. Heronly

medication is ibuprofen. She is 163 cm (5 ft 4 in) tall and weighs 87 kg (192 lb); BMI is

33 kg/m2. Her temperature is 37.3°C(99.2°F), pulse is 94/min, respirations are 16/min,

and blood pressure is 112/74 mm Hg. Examination shows mild hematomas at all

surgical sites. The abdomen is soft and nontender. There is no organomegaly. Bowel

sounds are normal. Laboratory studies show:Hemoglobin 10.3 g/dL Hematocrit

30%Leukocyte count 12,000/mm3 Platelet count 45,000/mm3 Which of the following is

the most likely cause of this patient's current findings? - Heparin-induced

thrombocytopenia

A 3-year-old girl with Down syndrome is brought to the physician because of a 1-week

history of frequent nosebleeds, decreased appetite, and lethargy. She takes no

medications. Her temperature is 38°C (100.4°F), pulse is 100/min, respirations are

20/min,and blood pressure is 80/45 mm Hg. Examination shows no other abnormalities

except for pallor. Laboratory studies show:Hemoglobin 6.5 g/dL Hematocrit

19%Leukocyte count 100,000/mm3 Segmented neutrophils 15%Atypical lymphocytes

85%Platelet count 45,000/mm3 Which of the following is the most likely mechanism of

these laboratory findings? - Infiltration of bone marrow by leukemic blasts

A 30-year-old woman, gravida 2, para 1, comes for her first prenatal visit at 26 weeks'

gestation. Uterine size is greater than expected for dates. Ultrasonography shows fetal

hydrops. Which of the following is the most appropriate next step in diagnosis? -

Maternal Rh status with antibody screening

A 65-year-old man has had increasingly severe headaches and diffuse muscle aches

during the past 3 months. He also has a 1-month history of jaw pain when chewing food

and decreasing visual acuity in his left eye. His temperature is 38°C (100.4°F). Visual

acuity in his left eye is 20/100, and the left optic disc is slightly atrophic. His muscle

strength is normal. Which of the following tests should be obtained next? -

Measurement of erythrocyte sedimentation rate

A 10-year-old boy has had anemia since birth. His spleen is five times normal size.

Splenectomy is indicated if the anemia is caused by which of the following disorders? -

Hereditary spherocytosis

A previously healthy 72-year-old man is brought to the physician because of weakness

and fatigue. His hemoglobin concentration is 9.2 g/dl, leukocyte count is 5400/mm3, and

platelet count is 350,000/mm3. A peripheral blood smear is shown. Which of the

following is the most likely cause of these findings? - Gastrointestinal blood loss

A 48-year-old man comes to the physician because of increasing bronzing of his skin,

weakness, and fatigue during the past 3 months. Physical examination shows bronzing

of the skin, hepatomegaly, and small testes. Serum studies show: Which of the

following best explains the findings in this patient? - Increased intestinal iron absorption

A 3-year-old boy and his 5-year-old brother bruise easily and have recurrent

hemarthrosis. Both parents are healthy, but the mother has two younger brothers with

the same symptoms and a maternal uncle who died at 8 years of age after mild head

trauma. Partial thromboplastin time is prolonged. The most likely defect involves which

of the following? - Factor VIII (antihemophilic factor)

An 81-year-old woman is admitted to the hospital because of a massive pulmonary

embolism from a deep venous thrombosis. Her platelet count is 160,000/mm3.

Appropriate pharmacotherapy is started. One week later, her platelet count is

55,000/mm3. The thrombocytopenia was most likely caused by a drug with which of the

following mechanisms of action? - Potentiates the action of antithrombin III

A 62-year-old woman with recurrent pulmonary emboli comes to the physician for a

follow-up examination. Physical examination shows no abnormalities. Laboratory

studies show a prothrombin time of 12 seconds. Warfarin therapy is begun. Which of

the following clotting factors is the first to be decreased by 50% after the initiation of

therapy? - VII (proconvertin)

A 40-year-old man is evaluated because his skin is extremely sensitive to sunlight.

Exposure to the sun causes the formation of vesicles and blisters on the skin, which

frequently take weeks to heal. He is diagnosed with a disorder caused by the increased

synthesis of compounds in the skin that are subject to excitation by visible light. Which

of the following biochemical pathways is most likely defective in this patient? - Heme

synthesis

A 53-year-old man, who recently returned from Africa, has fever, headache, and

abdominal discomfort. He received appropriate vaccinations prior to the trip. His

temperature is 39.4°C (103°F). Physical examination shows no other abnormalities. A

Wright-stained peripheral blood smear is shown. Which of the following is the most

likely diagnosis? - Malaria

A 10-year-old boy is brought to the physician because of a 4-day history of nosebleeds

and easy bruising. Three weeks ago, he had an upper respiratory tract infection.

Physical examination shows ecchymoses over the upper and lower extremities.

Laboratory studies show a hemoglobin concentration and leukocyte count within the

reference ranges and a decreased platelet count. A bone marrow smear shows an

increased number of megakaryocytes. Which of the following platelet abnormalities is

the most likely cause of the findings in this patient? - Antibodies directed against the

glycoprotein IIb/IIIa complex

A 14-year-old girl is brought to the physician because of a 4-month history of heavy

menstrual flow. Menarche occurred at the age of 13 years. Menses have occurred at

regular 30-day intervals. She has a history of frequent nosebleeds and easy bruisability.

Her father has had problems with nosebleeds and clotting. Physical examination shows

areas of mild gum bleeding and mild ecchymoses. Laboratory studies show: Which of

the following is the most likely diagnosis? - Von willebrand disease

A previously healthy 20-year-old woman comes to the emergency department because

of a 2-week history of fever, shaking chills, headaches, fatigue, and joint and muscle

pain. She recently spent the summer working as a lifeguard on Long Island, New York.

She has never traveled outside the USA. She underwent splenectomy for injuries

sustained in a motor vehicle collision at the age of 6 years. Her temperature is 39.1°C

(102.4°F). Physical examination shows no other abnormalities. A peripheral blood

smear shows small intraerythrocytic rings; the result of a polymerase chain reaction test

for Plasmodium is negative. This patient most likely acquired the causal organism via a

bite from which of the following? - Tick

A 25-year-old woman comes to the physician for a routine follow-up examination. Two

years ago, she underwent splenectomy as a result of injuries sustained in a motor

vehicle collision. Physical examination shows no abnormalities. A complete blood count

shows target erythrocytes. This finding is most likely the result of loss of function of

which of the following portions of the spleen? - Red pulp

A 55-year-old woman develops a headache, temperatures to 40°C (104 °F), a stiff neck,

and confusion. Her spleen was removed due to injuries sustained in a motor vehicle

collision 7 months ago. Which of the following organisms is most likely to be cultured

from the patient's cerebrospinal fluid? - Streptococcus pneumonia

A 35-year-old metal worker collapses after exposure to an unknown chemical at a

factory. He is dyspneic but is noncyanotic and smells of burnt almonds. The most

appropriate next step is to administer which of the following? - Amyl nitrite

A 42-year-old woman comes to the physician for an examination prior to employment.

She has no history of major medical illness. Her vital signs are within normal limits.

Physical examination shows no abnormalities. Laboratory studies show: Which of the

following is the most likely diagnosis? - Beta-thalassemia minor

A 30-year-old woman has had Hodgkin disease that was diagnosed 10 years ago and

was treated with radiation and chemotherapy for a 6-month period. She has remained in

remission for 10 years. She now feels weak and has petechiae and ecchymoses. A

diagnosis of acute myelogenous leukemia is made. Which of the following best explains

this course of events? - Therapy for Hodgkin disease causes mutations in

hematopoietic stem cells, and one mutant cell progresses to leukemia

A 38-year-old man is admitted to the hospital after sustaining a gunshot wound to the

abdomen. Broad-spectrum antibiotic therapy is initiated for complications from fecal

contamination of the peritoneal cavity. He has been taking warfarin since receiving an

artificial heart valve 6 years ago because of endocarditis secondary to intravenous drug

use. During the next 6 weeks, the warfarin dosage required to maintain his prothrombin

time progressively decreases. Which of the following best explains this finding? -

Vitamin K deficiency caused by depletion of the normal gut flora

A 2-month-old girl is brought to the physician for a follow-up examination 2 days after a

complete blood count was found to be abnormal. Her blood group is A, Rh-positive. She

was born at term to a healthy 23-year-old woman whose blood group is 0, Rh-positive.

Birth weight was 3890 g (8lb 9oz). Pregnancy and delivery were uncomplicated. The

patient has been active and feeding well. Her temperature is 37.6° C (99.7°F), pulse is

120/min, and respirations are 30/min. Physical examination shows no abnormalities.

Laboratory studies done since birth are shown. - Congenital neutropenia

A 14-year-old boy has had fatigue, intermittent right lower quadrant abdominal pain,

diarrhea, and a 5-kg (11-lb) weight loss over the past 6 months. A diagnosis of

inflammatory bowel disease limited to the terminal ileum is made. Absorption of which of

the following is most likely to be impaired in this patient? - Vitamin B12 (cobalamin)

Which of the following best explains why deoxygenated blood can carry more carbon

dioxide for a given Pco2 than oxygenated blood? - Deoxyhemoglobin is a better buffer

of hydrogen ions than oxyhemoglobin

An 18-year-old woman is brought to the emergency department 2 hours after she

ingested approximately 100 aspirin tablets in a suicide attempt. Physical examination

shows tachypnea. Two days after admission to the hospital, her hemoglobin

concentration is 12 g/dL. Test of the stool for occult blood is positive. Which of the

following additional hematologic findings is most likely abnormal in this patient? -

Bleeding time

A 45-year-old man is admitted to the hospital because of congestive heart failure. Two

first-degree relatives died in their 40s with dilated cardiomyopathy and cirrhosis.

Physical examination shows cardiac enlargement and generalized hyperpigmentation.

His serum glucose concentration is 320 mg/dl. Histologic examination of

endomyocardial tissue is most likely to show an excess of which of the following? - Iron