USMLE Step 1 Question 307

Question:

A 25-year-old athlete comes to your clinic and reports that she has not had her period for 8 months. She denies any weight changes and says her period has been normal since it began at age 13. She is 5’6″ and weighs 90 pounds. A pregnancy test is negative. What is the most likely cause of her amenorrhea?

Correct Answer: B.  Excessive exercise

While the most common cause of secondary amenorrhea is pregnancy, this patient has had a negative pregnancy test. In athletes, excessive exercise (Answer B) is known to cause amenorrhea. This patient is significantly underweight, which makes this option the most likely answer.

Early menopause (Answer A) is extremely unlikely in a 25-year-old. Hypothyroid patients (Answer C) tend to gain weight. Prolactinomas (Answer D) typically cause physical changes, including headaches and homonymous hemianopia. Resistance to LH and FSH (Answer E) would have manifested as primary amenorrhea during puberty.