A 19-year-old woman comes to the office due to amenorrhea for the last 5 months. The patient underwent menarche at age 14 and previously had regular menses every 28 days, typically lasting 4-5 days. She has no headaches, visual disturbances, heat intolerance, palpitations, hot flashes, or night sweats. The patient has no medical problems or previous surgeries. She takes no medications and does not use tobacco, alcohol, or illicit drugs. The patient is a national gymnastics champion and attends the local college. She has never been sexually active. Blood pressure is 110/60 mm Hg and pulse is 54/min. Height is 165 cm (5 ft 5 in) and BMI is 20 kg/m². Physical examination shows a muscular woman. She has mild facial acne but no thyromegaly or facial hair. Breast development and pubic hair are Tanner stage V. Pelvic examination reveals normal external genitalia, vagina, and cervix. On bimanual examination, there is a small, mobile uterus and no adnexal masses. Pregnancy test is negative. TSH and prolactin levels are normal. What is the most likely diagnosis in this patient?

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11ec25c8_d25d_c465_bc81_1f2f1975aa62_MD0003_00 This conditioned athlete has secondary amenorrhea likely due to functional hypothalamic amenorrhea. This type of amenorrhea often occurs in women with the athlete's triad: amenorrhea, osteoporosis, and an eating disorder. They are thought to have a relative caloric deficiency secondary to inadequate nutritional intake compared to the amount of energy expended. Women with this condition have been shown to have decreased levels of gonadotropin-releasing hormone (GnRH), with a subsequent decrease in LH secretion, resulting in estrogen deficiency. These women are at increased risk for conditions associated with estrogen deficiency, including infertility, vaginal atrophy, breast atrophy, and decreased bone mineral density (eg, osteopenia). (Choices A and B) Androgenic steroid use and congenital adrenal hyperplasia present with virilization (eg, male-pattern baldness, deepening voice, clitoromegaly) and hypertension. Patients using androgenic steroids also present with aggressive behavior and mood disorders, which are not seen in this patient. (Choice D) Ovarian fibrothecoma, a type of ovarian sex cord-stromal tumor, may secrete androgens but more commonly secretes estrogen. This patient has no evidence of excess androgens (eg, hirsutism) or estrogen (eg, breast tenderness) and no adnexal mass. (Choice E) Patients with polycystic ovarian syndrome have signs of androgen excess (eg, severe nodulocystic acne on the chest and back), obesity, and enlarged ovaries on examination. This patient has mild acne, but her normal BMI and pelvic examination make this diagnosis less likely. (Choice F) Patients with primary ovarian insufficiency (POI) typically have vasomotor symptoms (eg, hot flashes, night sweats) associated with amenorrhea. POI is typically associated with a concomitant autoimmune disorder or Turner syndrome. (Choice G) A patient with subclinical hyperthyroidism is typically asymptomatic, with a decreased TSH level. Educational objective: Secondary amenorrhea is relatively common in female athletes and results from hypothalamic amenorrhea (eg, GnRH deficiency). The subsequent decreased LH secretion and estrogen deficiency result in decreased bone mineral density. References: Neuroendocrine control of ovulation. (http://www.ncbi.nlm.nih.gov/pubmed/22283375)

A 19-Year-Old Woman Comes to the Office Due to Amenorrhea