USMLE USMLE Certifications USMLE Questions & Answers

• Question 541:

  A 17-year-old girl is brought to the physician by her mother because she has not had a menstrual period for 6 months. The patient is unconcerned about the lack of menses. Menarche occurred at the age of 12 years, and menses had occurred at regular 28-day intervals until they became irregular 1 year ago. She is a member of her high school gymnastics team. She appears emaciated. She is 163 cm (5 ft 4 in) tall and weighs 40 kg (88 lb); BMI is 15 kg/m2. Her pulse is 54/min, and blood pressure is 80/50 mmHg. Which of the following is the most likely cause of this patient's amenorrhea?

  A. Hyperthyroidism

  B. Hypogonadotropic hypogonadism

  C. Hypothyroidism

  D. Polycystic ovarian syndrome

  E. Prolactinoma

  Correct Answer: B

• Question 542:

  A 49-year-old woman comes to the physician for a follow-up examination. She has a strong family history of coronary artery disease. Her blood pressure has ranged from 150/95 mmHg to 130/85 mmHg during the previous three visits within the past 2 months. Her blood pressure today is 140/90 mmHg. Physical examination shows no other abnormalities. Laboratory studies show:

  

  Treatment with atorvastatin and losartan is initiated. Which of the following serum findings is most likely to occur in this patient?

  

  A. Option A

  B. Option B

  C. Option C

  D. Option D

  E. Option E

  Correct Answer: C

• Question 543:

  A 15-year-old girl comes to the physician because of a 3-month history of acne. Breast and pubic hair development began at the age of 12 years. Menarche occurred at the age of 14 years. Physical examination shows scattered open and closed comedones over the cheeks and forehead. Breast and pubic hair development is Tanner stage 5. Which of the following is the most likely underlying cause of this patient's acne?

  A. Decreased parasympathetic stimulation to the sebaceous glands

  B. Increased estrogen stimulation of the sebaceous glands

  C. Increased responsiveness of the sebaceous glands to follicle-stimulating hormone

  D. Increased sympathetic stimulation to the sebaceous glands

  E. Stimulation of the sebaceous glands by androgens

  Correct Answer: E

• Question 544:

  A 30-year-old woman, gravida 2, para 0, aborta 1, at 28-weeks' gestation comes to the office for a prenatal visit. She has had one previous pregnancy resulting in a spontaneous abortion at 12-weeks' gestation. Today, her vital signs are within normal limits. Physical examination shows a uterus consistent in size with a 28-week gestation. Fetal ultrasonography shows a male fetus with no abnormalities. Her blood group is O, Rh-negative. The father's blood group is B, Rh-positive. The physician recommends administration of Rho (D) immune globulin to the patient. This treatment is most likely to prevent which of the following in this mother?

  A. Development of natural killer cells

  B. Development of polycythemia

  C. Formation of antibodies to RhD

  D. Generation of IgM antibodies from fixing complement in the fetus

  E. Immunosuppression caused by RhD on erythrocytes from the fetus

  Correct Answer: C

• Question 545:

  A 52-year-old woman begins pharmacotherapy after being diagnosed with type 2 diabetes mellitus. Four weeks later, her hepatic glucose output is decreased, and target tissue glucose uptake and utilization are increased. Which of the following drugs was most likely prescribed for this patient?

  A. Acarbose

  B. Glyburide

  C. Metformin

  D. Nateglinide

  E. Repaglinide

  Correct Answer: C

• Question 546:

  A sexually active 23-year-old man with multiple sex partners has dysuria and a yellow urethral exudate. Gram stain of the exudate shows numerous neutrophils, many that contain intracellular gram-negative diplococci. He has had three similar episodes of urethritis over the past 2 years. Which of the following properties of the infecting organism best explains the reinfection?

  A. Antigenic variation

  B. Catalase

  C. Inhibition of B-lymphocyte function

  D. Inhibition of T-lymphocyte function

  E. Polysaccharide capsule

  Correct Answer: A

• Question 547:

  A 17-year-old girl is brought to the emergency department 15 minutes after being stung by a bee. She has mild light-headedness but no difficulty swallowing. Her temperature is 37.1°C (98.8°F), pulse is 100/min, respirations are 30/min, and blood pressure is 115/70 mmHg. Physical examination shows no urticaria. Bilateral wheezing is heard on auscultation of the chest. Which of the following types of drugs is the most appropriate pharmacotherapy for this patient?

  A. α1-Adrenergic agonist

  B. α2-Adrenergic agonist

  C. α1-Adrenergic antagonist

  D. β2-Adrenergic agonist

  E. β2-Adrenergic antagonist

  Correct Answer: D

• Question 548:

  A 2-year-old boy is brought to the physician for a well-child examination. He was delivered at term after an uncomplicated pregnancy. His birth weight was 3500 g (7lb11oz), and Apgar scores were 8 and 10 at 1 and 5 minutes, respectively. At the age of 15 months, physical examination showed no abnormalities, but he was not yet talking. Both of his parents had learning difficulties in school, and his mother stopped attending after the 10th grade. He has a maternal uncle with cognitive disabilities. He is at the 25th percentile for height, 15th percentile for weight, and 90th percentile for head circumference. He appears irritable, he resists making eye contact, and he is flapping his hands. Which of the following is the most likely cause of this patient's condition?

  A. Creation of an alternative splice site

  B. Frameshift mutation

  C. Missense mutation

  D. Nonsense mutation

  E. Trinucleotide repeat expansion

  Correct Answer: E

• Question 549:

  A 31-year-old woman with type 2 diabetes mellitus comes to the physician because of an oozing, foul-smelling wound on her foot for 2 days. Physical examination shows a 4-cm, necrotizing wound with a purplish black discoloration over the heel. Crepitant bullae producing profuse amounts of serous drainage are seen. A Gram stain of a tissue biopsy specimen shows gram-positive rods. The causal organism most likely produces which of the following virulence factors?

  A. Endotoxin

  B. Fimbriae

  C. Pneumolysin

  D. Polysaccharide capsule

  E. α-Toxin

  Correct Answer: E

• Question 550:

  A 10-month-old boy is brought to the physician because of a 4-day history of fever and cough. His illness began with low-grade fever and copious, clear nasal discharge. Two days ago he developed a moist, nonproductive cough and rapid breathing. He has received all scheduled childhood immunizations. He attends a large day-care center and has three school-aged siblings. His temperature is 38°C (100.4°F), pulse is 101/min, respirations are 38/min, and blood pressure is 85/60 mmHg. Physical examination shows nasal flaring and rhinorrhea. Chest examination shows intercostal retractions along with bilateral, diffuse wheezes and expiratory rhonchi. The infectious agent of this patient's condition most likely has which of the following properties?

  A. DNA genome

  B. Double-stranded nucleic acid genome

  C. Mature virion lacking viral polymerase

  D. Mediation of cell entry via a fusion protein

  E. Viability on surfaces for several weeks

  Correct Answer: D