A 16-year-old girl presents to her pediatrician for a routine physical. Her mother expresses concern that her daughter has not yet had her first menstrual period. The girl reports normal breast development and growth spurt. Physical exam reveals normal external female genitalia, breast Tanner stage IV, and axillary/pubic hair Tanner stage IV. Her height is at the 50th percentile for her age. What is the most appropriate initial diagnostic test?
✓ Correct Answer: Option B
This patient has primary amenorrhea with normal secondary sexual characteristics, indicating estrogen production. The next step is to assess the hypothalamic-pituitary-ovarian axis with FSH and LH levels to differentiate between central (hypothalamic/pituitary) and ovarian causes.