Adolescent menstrual irregularity

Amenorrhea and oligomenorrhea in the adolescent female are often the result of anovulation due to an immature hypothalamic-pituitary-ovarian axis. A careful history, physical examination and selected laboratory tests can help to differentiate this type of transient menstrual irregularity from the large number of endocrine and anatomic abnormalities that also present in this age group. The HPO axis is not fully mature at menarche. Since the positive feedback response to estrogen, which allows ovulation, is frequently absent in the immediate postmenarchial period, menstrual irregularity is common: 55% of cycles are anovulatory in the 1st year. With further maturation of the HPO axis a pattern of regular ovulatory cycles emerges. Basic evaluation is indicated if menarche does not occur by age 16 or if secondary sexual development does not begin by age 14. Secondary amenorrhea is the absence of menses for at least 3 months in a patient who previously had established cycles. Causes of amenorrhea in adolescents include pregnancy, drugs and systemic diseases, hypothalamic and pituitary amenorrhea, postpill amenorrhea, hyperprolactinemia, androgen resistance, congenital anomalies of the genital tract, and androgen excess.