Kaplan USMLE Step 2: Patient has not yet had a menstrual period

If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 2 exam, you might want to know which questions are most often missed by test-prep takers. Check out this example from Kaplan Medical, and read an expert explanation of the answer. Also check out all posts in this series.

An 18-year-old female comes to the physician because she has not yet had a menstrual period. The patient has a history of congenital hearing loss for which she uses hearing aids and has a decreased sense of smell. She had surgery to repair a cleft palate. Her mother has type 2 diabetes mellitus and her father has hypertension. Vital signs are within normal limits. Height and weight are at the 55th and 50th percentile for age respectively.

Physical examination shows Tanner stage 1 of the breasts and Tanner stage 3 of pubic hair. The cervix is normal and the vaginal mucosa is deep red. The labia and vulva are pale and small. Bimanual pelvic examination is normal. A urine pregnancy test is negative.

Which of the following is the most likely diagnosis?

A. Constitutional delay of growth and puberty

B. Functional hypogonadotropic hypogonadism

C. Kallmann syndrome

D. Nonclassic congenital adrenal hyperplasia

E. Turner syndrome

The correct answer is C.

This patient presents with primary amenorrhea, absent breast development, a red vaginal mucosa, pale and small external genitalia, and a history of cleft palate, congenital hearing loss, and anosmia, a presentation consistent with Kallman syndrome (i.e., isolated gonadotropin deficiency or familial hypogonadotropic hypogonadism).

Choice A. Constitutional delay of growth and puberty can present with primary amenorrhea and absent breast development; however, pubic hair is typically absent.