Amenorrhea in a Teenager

In Episode 15 of Med School Question of the Week for USMLE, Luke Maxfield, MedSchoolCoach expert tutor, answers this medical school question: A 17-year-old girl is brought to the physician by her mother because she has not had a menstrual period for 6 months. The patient is unconcerned about her lack of menses. Menarche occurred at the age of 12 years, and menses had occurred at regular 28 day intervals until they became irregular one year ago. She is a member of her high school gymnastics team. On physical examination she appears emaciated. She is 164cm tall and weighs 40kg. BMI is 15kg/m². Her pulse is 54/min and blood pressure is 80/50. Her skin has prominent fine non-pigmented hairs. Which of the following is most likely to be the cause of this patient’s amenorrhea?

• Hyperthyroidism
• Hypogonadotropic hypogonadism
• Hypothyroidism
• Polycystic ovarian syndrome
• Prolactinoma