USMLE USMLE Certifications USMLE-STEP-3 Questions & Answers

• Question 391:

  A 10-year-old male has a history of seizures which are controlled with dilantin. The child also has asthma and often uses an albuterol inhaler. Which of the following asthma medications can lower the seizure threshold in children?

  A. theophylline

  B. salmeterol

  C. beclomethasone

  D. montelukast

  E. nedocromil

  Correct Answer: A Section: (none)

  Explanation:

  Theophylline, a methylxanthine, has an excitatory effect on the CNS. This serious side effect, in conjunction with its very narrow therapeutic window, has made theophylline use very uncommon. The use of any of the other medications listed would be recommended before consideration of the use of theophylline.

• Question 392:

  Use of which medication can result in enamel staining of primary teeth?

  A. erythromycin

  B. ciprofloxacin (Cipro)

  C. cephalexin

  D. trimethoprim/sulfamethoxazole (Septra)

  E. tetracycline

  Correct Answer: E Section: (none)

  Explanation:

  Gray or brown teeth staining can be seen with the use of tetracycline in children who still have their primary teeth. Tetracyclines are usually safe as a single course in normal doses in younger children. The use of tetracyclines in children is typically safe after 8 years of age. Teeth staining can also be seen in the children of women who took tetracycline while pregnant.

• Question 393:

  Parents bring their 6-year-old son to the emergency room following an acute onset of vomiting and combative behavior. The parents state that the child has recently had chickenpox. They have been giving him medication to reduce his fever, which has been as high as 102 F. Which medication is the likely cause of his current condition?

  A. acetaminophen

  B. aspirin

  C. amoxicillin

  D. ibuprofen

  E. diphenhydramine

  Correct Answer: B Section: (none)

  Explanation:

  Historically, Reye's syndrome was a cause of hepatitis and encephalitis. It was seen in children with influenza or varicella who were given aspirin. Widespread knowledge of this issue, resulting in an almost complete cessation of the use of aspirin in children, has made Reye's syndrome a very rare occurrence.

• Question 394:

  A 4-year-old boy returns for his second visit to the emergency room. Three days ago he was brought in with a 4-day history of fever up to 102°F. At that time, his physical examination was significant for injection of the oropharynx and an enlarged left anterior cervical lymph node. His left TM was nonbulging and nonerythematous. He was sent home on amoxicillin with a diagnosis of streptococcal pharyngitis. He returns today with a persistent fever, edema of both hands, bilateral conjunctivitis, and a polymorphous truncal rash.

  What is the treatment for this condition?

  A. a tapering dose of prednisone

  B. high-dose aspirin and IVIG

  C. IVIG alone

  D. admission to the hospital for IV antibiotics and fluids

  E. a 2-week course of antibiotics and a shot of prednisone

  Correct Answer: B Section: (none)

  Explanation:

  Kawasaki disease is the second most common systemic vasculitis in children. The diagnosis requires the presence of fever for at least 5 days and four of the five criteria: bilateral conjunctivitis (generally nonpurulent); oropharyngeal mucosal changes including pharyngeal injection, strawberry tongue, or injection or fissuring of the lips; nonfluctuant cervical lymphadenopathy, usually unilateral; polymorphous rash that is primarily truncal; and changes of the peripheral extremities, including edema or erythema of hands and feet, or desquamation of the finger/ toes, usually beginning periungally. The treatment of Kawasaki disease consists of high-dose aspirin and IVIG as a single dose infused over 12 hours. The role of corticosteroid as treatment is controversial. This therapy was abandoned after an initial report citing increased rates of coronary artery aneurysms. A few recent studies reveal successful treatment with methylprednisolone in children who failed therapy of IVIG, but it is not first line.

• Question 395:

  A 4-year-old boy returns for his second visit to the emergency room. Three days ago he was brought in with a 4-day history of fever up to 102°F. At that time, his physical examination was significant for injection of the oropharynx and an enlarged left anterior cervical lymph node. His left TM was nonbulging and nonerythematous. He was sent home on amoxicillin with a diagnosis of streptococcal pharyngitis. He returns today with a persistent fever, edema of both hands, bilateral conjunctivitis, and a polymorphous truncal rash.

  What is the most likely diagnosis?

  A. rickettsial infection

  B. drug hypersensitivity reaction

  C. measles

  D. Kawasaki disease

  E. Scarlet fever

  Correct Answer: D Section: (none)

  Explanation: Kawasaki disease is the second most common systemic vasculitis in children. The diagnosis requires the presence of fever for at least 5 days and four of the five criteria: bilateral conjunctivitis (generally nonpurulent); oropharyngeal mucosal changes including pharyngeal injection, strawberry tongue, or injection or fissuring of the lips; nonfluctuant cervical lymphadenopathy, usually unilateral; polymorphous rash that is primarily truncal; and changes of the peripheral extremities, including edema or erythema of hands and feet, or desquamation of the finger/ toes, usually beginning periungally. The treatment of Kawasaki disease consists of high-dose aspirin and IVIG as a single dose infused over 12 hours. The role of corticosteroid as treatment is controversial. This therapy was abandoned after an initial report citing increased rates of coronary artery aneurysms. A few recent studies reveal successful treatment with methylprednisolone in children who failed therapy of IVIG, but it is not first line.

• Question 396:

  A 17-year-old is brought by emergency medical services to the emergency room in a postictal state after a witnessed grand mal seizure. No family member is available and the patient is unable to answer questions. Afriend who is with him says that he takes some medicine for seizures, but he doesn't know the name. On examination, you note that he has prominent gingival hyperplasia. Of the medications listed below, which one is he most likely to be taking?

  A. phenobarbital

  B. valproic acid

  C. carbamazipine

  D. phenytoin E. levitiracetam (Keppra)

  Correct Answer: D Section: (none)

  Explanation:

  Gingival hyperplasia is a common side effect of chronic phenytoin administration. This will resolve with cessation of the medication. None of the other anticonvulsants listed will result in this problem.

• Question 397:

  What is the major mode of transmission of HIV infection in young children today?

  A. biting

  B. blood transfusion

  C. vertical transmission

  D. horizontal transmission

  E. sexual abuse

  Correct Answer: C Section: (none)

  Explanation:

  Vertically transmitted, or perinatally acquired, HIV is the most common mode of transmission in pediatric patients. Maternal health, maternal viral load, third trimester antiretroviral therapy, and mode of delivery all affect the rate of perinatal acquisition.

• Question 398:

  A 16-year-old woman comes to see you for a yearly physical examination. Her only concern is that her periods are very irregular, and she desires oral contraceptives to regulate them. She relates that menarche was at 12 years, of age and that her periods have always been irregular. On examination, she is a markedly obese woman with a body mass index of 35 and with normal linear growth. She has some coarse

  facial hair down both of her checks as well as cystic acne along her hairline. On the nape of her neck she is

  noted to have acanthosis nigricans. She has tanner 4 breast development as well as tanner 4 pubic hair.

  Her urinalysis in the office is normal.

  What would be the best intervention to achieve the best long-term outcome in this woman?

  A. Begin low-dose subcutaneous insulin to prevent diabetes mellitus.

  B. Begin daily corticosteroid therapy to suppress testosterone secretion.

  C. Begin a regimen of lifestyle changes, including dietary and exercise alterations.

  D. Begin levothyroxine (Synthroid) for control of weight gain.

  E. Oophorectomy to decrease hormone levels.

  Correct Answer: C Section: (none)

  Explanation:

  This clinical vignette describes an adolescent female with PCOS. PCOS is commonly seen in obese adolescent females with anovulatory menstrual cycles, hirsutism, and generalized virilization (acne). Commonly, PCOS patients will have glucose insensitivity and manifest features of type II diabetes mellitus. The diagnosis of PCOS may be difficult to ascertain. A pelvic ultrasound demonstrating "polycystic ovaries" (the string of pearls sign) may be quite helpful. Girls with PCOS will typically have elevated triglycerides, low HDL cholesterol, and a suppressed prolactin. As indicated above, PCOS girls also often have glucose insensitivity and an abnormal glucose tolerance test. The most effective therapy in PCOS involves lifestyle alterations (weight loss and exercise) and hormonal regulation of ovulation. The hypoglycemic agent metformin is now being used to assist in the management of PCOS. Occasionally, subcutaneous insulin may be effective in controlling hyperglycemia, but this will not prevent diabetes mellitus.

• Question 399:

  A 16-year-old woman comes to see you for a yearly physical examination. Her only concern is that her periods are very irregular, and she desires oral contraceptives to regulate them. She relates that menarche was at 12 years, of age and that her periods have always been irregular. On examination, she is a markedly obese woman with a body mass index of 35 and with normal linear growth. She has some coarse facial hair down both of her checks as well as cystic acne along her hairline. On the nape of her neck she is noted to have acanthosis nigricans. She has tanner 4 breast development as well as tanner 4 pubic hair. Her urinalysis in the office is normal.

  Which of the following would confirm your diagnosis?

  A. ultrasound of the pelvis showing multiple ovarian follicles ("string of pearls" sign)

  B. a low serum thyroid-stimulating hormone (TSH) level

  C. an elevated serum prolactin level

  D. elevated high-density lipoprotein (HDL) with low triglycerides

  E. normal glucose tolerance test

  Correct Answer: A Section: (none)

  Explanation:

  This clinical vignette describes an adolescent female with PCOS. PCOS is commonly seen in obese adolescent females with anovulatory menstrual cycles, hirsutism, and generalized virilization (acne). Commonly, PCOS patients will have glucose insensitivity and manifest features of type II diabetes mellitus. The diagnosis of PCOS may be difficult to ascertain. A pelvic ultrasound demonstrating "polycystic ovaries" (the string of pearls sign) may be quite helpful. Girls with PCOS will typically have elevated triglycerides, low HDL cholesterol, and a suppressed prolactin. As indicated above, PCOS girls also often have glucose insensitivity and an abnormal glucose tolerance test. The most effective therapy in PCOS involves lifestyle alterations (weight loss and exercise) and hormonal regulation of ovulation. The hypoglycemic agent metformin is now being used to assist in the management of PCOS. Occasionally, subcutaneous insulin may be effective in controlling hyperglycemia, but this will not prevent diabetes mellitus.

• Question 400:

  A 16-year-old woman comes to see you for a yearly physical examination. Her only concern is that her periods are very irregular, and she desires oral contraceptives to regulate them. She relates that menarche was at 12 years, of age and that her periods have always been irregular. On examination, she is a markedly obese woman with a body mass index of 35 and with normal linear growth. She has some coarse facial hair down both of her checks as well as cystic acne along her hairline. On the nape of her neck she is noted to have acanthosis nigricans. She has tanner 4 breast development as well as tanner 4 pubic hair. Her urinalysis in the office is normal.

  What is the most likely cause of her irregular periods?

  A. hypothyroidism

  B. polycystic ovarian syndrome (PCOS)

  C. late-onset congenital adrenal hyperplasia (CAH)

  D. Cushing syndrome

  E. testosterone insensitivity

  Correct Answer: B Section: (none)

  Explanation:

  This clinical vignette describes an adolescent female with PCOS. PCOS is commonly seen in obese adolescent females with anovulatory menstrual cycles, hirsutism, and generalized virilization (acne). Commonly, PCOS patients will have glucose insensitivity and manifest features of type II diabetes mellitus. The diagnosis of PCOS may be difficult to ascertain. A pelvic ultrasound demonstrating "polycystic ovaries" (the string of pearls sign) may be quite helpful. Girls with PCOS will typically have elevated triglycerides, low HDL cholesterol, and a suppressed prolactin. As indicated above, PCOS girls also often have glucose insensitivity and an abnormal glucose tolerance test. The most effective therapy in PCOS involves lifestyle alterations (weight loss and exercise) and hormonal regulation of ovulation. The hypoglycemic agent metformin is now being used to assist in the management of PCOS. Occasionally, subcutaneous insulin may be effective in controlling hyperglycemia, but this will not prevent diabetes mellitus.