Getting ready for the United States Medical Licensing Examination® (USMLE®) is no easy feat, but we’re sharing expert insights to help give you a leg up. Take a look at the exclusive scoop on this month’s most-missed USMLE test prep question. Think you have what it takes to rise above your peers? Test your knowledge of the endocrine system with this question. Once you’ve got this question under your belt, be sure to test your knowledge with other posts in this series.
Ready. Set. Go.
This month’s question that stumped most students
A 40-year-old woman comes to the physician because of epigastric pain, especially after meals. Vital signs are within normal limits. Physical examination shows multiple angiofibromas and lipomas. There is mild epigastric tenderness with deep palpation. Laboratory studies show hypercalcemia and elevated serum parathyroid hormone. Exploratory surgery of the neck shows diffuse hyperplasia of all four parathyroid glands. Which of the following laboratory studies is most appropriate to confirm the likely diagnosis?
A. Pentagastrin-simulated calcitonin secretion
B. Serum epinephrine
C. Serum gastrin
D. Serum norepinephrine
E. Urinary epinephrine/norepinephrine ratio
The correct answer is C.
Kaplan says, here’s why
Both multiple endocrine neoplasia type I (MEN I) and multiple endocrine neoplasia type IIa (MEN IIa) can present with parathyroid hyperplasia. However, angiofibromas and lipomas are more typical of MEN I than MEN IIa. In MEN I, parathyroid hyperplasia and/or adenomas are associated with pancreatic and duodenal endocrine tumors and endocrine hyperplasia. The most common secretory product of the pancreatic and duodenal endocrine lesions is gastrin, which can lead to peptic ulcers, as in this patient with epigastric pain and tenderness. Pituitary adenomas may also occur in MEN I.
Why you shouldn’t choose the other answers
Read these explanations to understand the important rationale for each answer to help you prepare with future studying.
Choice A: Pentagastrin-stimulated calcitonin secretion is a marker for medullary carcinoma of the thyroid, which is a component of MEN II.
Choice B: Epinephrine (adrenaline) is produced by pheochromocytomas that occur as part of MEN II; serum epinephrine levels
Choice D: Serum norepinephrine is usually not helpful in the diagnosis of pheochromocytoma because serum catecholamines can be increased by hypoglycemia, strenuous exertion and central nervous system disease.
Choice E: Urinary epinephrine/norepinephrine ratios may be used for screening for pheochromocytomas.
Want more help with USMLE test prep questions? Check out the first post in AMA Wire’s Tutor Talk series. Also, review this definitive USMLE Step 1 guide, which features expert tips on test-taking strategies and preparation.
