Etiology and management of amenorrhea in adolescent and young adult women.

In this article, we will review the etiology and management of amenorrhea in adolescent and young adult women, beginning with the diagnostic work-up and followed by etiologies organized by system. Most cases of amenorrhea are caused by dysfunction of the hypothalamic-pituitary-ovarian (HPO) axis, which is the major regulator of the female reproductive hormones: estrogen and progesterone.  We begin by reviewing hypothalamic etiologies, including eating disorders and relative energy deficiency in sport. Then, pituitary causes of amenorrhea are reviewed, including hyperprolactinemia, empty sella syndrome, Sheehan's syndrome and Cushing's syndrome. Next, ovarian causes of amenorrhea are reviewed, including polycystic ovarian syndrome and primary ovarian insufficiency. Finally, other etiologies of amenorrhea are discussed, including thyroid disease, adrenal disease and reproductive tract anomalies. In conclusion, there is a wide and diverse range of causes of amenorrhea in adolescents that originate from any level of the HPO axis, as well as anatomic and chromosomal etiologies.   Treatment should be focused on the underlying cause. Preservation of bone density and risk of fractures should be discussed with amenorrheic patients since many causes of amenorrhea can result in decreased bone density and may be irreversible.