USMLE USMLE Certifications USMLE Questions & Answers

• Question 521:

  A placebo-controlled clinical trial is conducted to assess whether a new antihypertensive drug is more effective than standard therapy. A total of 5000 patients with essential hypertension are enrolled and randomly assigned to one of two groups: 2500 patients receive the new drug and 2500 patients receive placebo. If the alpha is set at 0.01 instead of 0.05, which of the following is the most likely result?

  A. Significant findings can be reported with greater confidence

  B. The study will have more power

  C. There is a decreased likelihood of a Type II error

  D. There is an increased likelihood of statistically significant findings

  E. There is an increased likelihood of a Type I error

  Correct Answer: A

• Question 522:

  A male stillborn is delivered at 32 weeks' gestation to a 30-year-old woman. The pregnancy was complicated by oligohydramnios. Examination of the stillborn shows the absence of a urethral opening. Which of the following additional findings is most likely in this stillborn?

  A. Congenital diaphragmatic hernia

  B. Intralobar

  C. Pulmonary hypoplasia

  D. Situs inversus

  E. Tracheoesophageal fistula

  Correct Answer: C

• Question 523:

  A 33-year-old man undergoes a radical thyroidectomy for thyroid cancer. During the operation, moderate hemorrhaging requires ligation of several vessels in the left side of the neck. Postoperatively, serum studies show a calcium concentration of 7.5 mg/dL, albumin concentration of 4 g/dL, and parathyroid hormone concentration of 200 pg/mL. Damage to which of the following vessels caused the findings in this patient?

  A. Branch of the costocervical trunk

  B. Branch of the external carotid artery

  C. Branch of the thyrocervical trunk

  D. Tributary of the internal jugular vein

  E. Tributary of the left brachiocephalic vein

  F. Tributary of the right brachiocephalic vein

  Correct Answer: C

• Question 524:

  A 22-year-old woman contacts a medical student and asks if he would like to join her for dinner. The student met the woman when he was assigned to her care during her 2-week hospitalization for treatment of major depressive disorder. He has not treated or seen the patient since she was discharged from the hospital. He is attracted to this former patient and would be interested in dating her. Which of the following is the most appropriate action by the medical student regarding this patient's invitation?

  A. He can date her because he was a medical student, not a physician, when he contributed to her care

  B. He can date her because she is no longer his patient

  C. He can date her, but only after at least 1 year has passed since he treated her

  D. He cannot date her because she was once his psychiatric patient

  E. He cannot date her unless she agrees never to seek care at his hospital in the future

  Correct Answer: D

• Question 525:

  A 73-year-old woman comes to the physician because of a 2-month history of diffuse weakness and tingling of her arms and legs. Neurologic examination shows weakness of the extensor and flexor muscles of the lower extremities. Knee and ankle deep tendon reflexes are exaggerated. Sensation to vibration and position is decreased in all extremities, but the decrease is more prominent in the lower extremities than in the upper extremities. This patient most likely has a deficiency of which of the following vitamins?

  A. Niacin

  B. Vitamin B1 (thiamine)

  C. Vitamin B2 (riboflavin)

  D. Vitamin B6 (pyridoxine)

  E. Vitamin B12 (cyanocobalamin)

  Correct Answer: E

• Question 526:

  A 5-year-old boy is admitted to the hospital because of a 1-week history of fever and increasingly severe abdominal discomfort. At the age of 7 months, he was treated for osteomyelitis caused by Aspergillus fumigatus. He has been admitted to the hospital three times during the past 4 years for severe pneumonia. He appears moderately ill. His temperature is 39°C (102.2°F). Abdominal examination shows an enlarged, tender liver. Ultrasonography of the abdomen shows an intrahepatic abscess. Culture of the abscess fluid grows Staphylococcus aureus. Further analysis shows failure of the neutrophils to undergo an oxidative burst when exposed to S. aureus. This patient has an increased susceptibility to infection as a result of which of the following abnormalities?

  A. Deficient leukocyte production

  B. Failure of leukocytes to migrate between endothelial cells

  C. Failure of leukocytes to roll along the endothelial surface

  D. Inability of leukocytes to ingest microorganisms

  E. Inability of leukocytes to kill intracellular microorganisms

  Correct Answer: E

• Question 527:

  A 14-year-old boy is brought to the physician for a physical examination prior to participating in sports. He appears reluctant to remove his shirt for the examination, and says that he is embarrassed because he has grown breasts during the past year. He is at the 50th percentile for height and weight. Physical examination shows bilateral 1.5-cm fibroglandular masses located beneath the nipple-areolar complex and normal penis and testes. Pubic hair development is Tanner stage 3. Serum concentrations of gonadotropic hormones, estrogens, and testosterone are within the reference ranges. Which of the following is the most likely cause of this patient's breast enlargement?

  A. Breast adenocarcinoma

  B. Estradiol-secreting Leydig cell tumor

  C. Peutz-Jeghers syndrome

  D. Seminiferous tubule dysgenesis (Klinefelter syndrome)

  E. Normal development

  Correct Answer: E

• Question 528:

  A 72-year-old woman comes to the physician because of a 2-month history of painless swelling of both ankles. She also reports shortness of breath with exertion and when lying down. She has been awakened from sleep by shortness of breath. She has not had chest pain. Her pulse is 96/min and regular, respirations are 24/min, and blood pressure is 128/76 mm Hg. Jugular venous pressure is 15 cm H2O. Pulmonary examination shows crackles at both lung bases. Cardiac examination shows a regular rhythm and a soft S3. A grade 3/6 holosystolic murmur is heard best at the apex, radiating to the axilla. There is 2+ pitting edema of the lower legs and ankles. Which of the following is most likely to confirm the diagnosis?

  A. Measurement of serum troponin I concentration

  B. ECG

  C. Exercise stress test

  D. Echocardiography

  E. Pulmonary artery catheterization

  Correct Answer: D

• Question 529:

  A 64-year-old man with non-Hodgkin lymphoma comes to the physician because of a 3-week history of progressive numbness in his hands and feet and weakness in his legs when he stands. He received his third course of chemotherapy 4 weeks ago. Physical examination shows areflexia. Which of the following drugs is the most likely cause of these adverse effects?

  A. Bleomycin

  B. Cyclophosphamide

  C. Cytarabine

  D. Doxorubicin

  E. Fluorouracil

  F. Methotrexate

  G. Vincristine

  Correct Answer: G

• Question 530:

  During an experiment, drug X is added to a muscle bath containing a strip of guinea pig intestinal smooth muscle. Agonists are added to the bath, and the resultant effects on muscle tension are shown in the table.

  

  Which of the following types of drugs is most likely to produce effects most similar to those of drug X?

  A. α1-Adrenergic antagonist

  B. β-Adrenergic antagonist

  C. Cholinesterase inhibitor

  D. Monoamine oxidase inhibitor

  E. Muscarinic antagonist

  Correct Answer: C