Importance of Regular Monthly Menstruation
Despite the many common misconceptions, monthly menstrual flow offers several critical biologic roles. Specifically, a healthy cycle validates usually normal reproductive anatomy precluding outflow tract obstruction, indicating probable ovulation to facilitate fertility, and establishes protection from endometrial hyperplasia (excessive uterine lining growth potentially leading to cancer). These assumptions are not always valid as there are specific exceptions.
Evaluation & Management of Amenorrhea
The lack of menstrual flow is diagnosed as Amenorrhea: Primary (PA) occurs before menarche (the pubertal event of first menses); and secondary (SA) results after menarche. Establishing the diagnosis of PA has resulted in confusion due to the recent shift toward earlier puberty and the range of accepted delayed puberty. Nevertheless, a reasonable approach uses the knowledge that ovarian estrogen production is responsible for telarche (pubertal onset of breast development) and simultaneous endometrial proliferation (uterine lining growth) until the inevitable break through bleeding of menarche. As a result, no menses three years after telarche or no menses by age 15 irrespective of telarche are safe definitions of PA. Historically, the accepted definition of SA excluding pregnancy or lactation, is greater than six months without menses, however evaluation is warranted when menstrual interval greater than 35 days or less than nine menses per year.
Etiologies of PA can be classified based on determining the status of two important organ systems: breast development and a uterus. The former demonstrates appropriate estrogen production from the ovaries. The latter represents either a lack of Antimullerian hormone production by the Sertoli cells of the testis, or a defect in mullerian development (reproductive anatomy). Mullerian agenesis usually presents with an absent uterus and a blind ending or absent vagina but must be distinguished from Androgen Insensitivity Syndrome since the latter karyotype is 46, XY and compels removal of the intra-abdominal gonad. Alternatively, gonadal dysgenesis (typically Turner’s syndrome) presents with streak gonads, markedly elevated FSH levels and a sexually infantile patient from lack of estrogen production. Other hypothalamic disorders which may present as PA are Kallman’s syndrome (lack of hypothalamic GnRH neuronal development) and a Craniopharyngioma (cerebral tumor resulting in delayed puberty).
Causes of Amenorrhea
The World Health Organization (WHO) has classified the causes of amenorrhea (usually secondary) into three groups. Group I is due to hypothalamic dysfunction (HD) resulting in hypogonadotropic hypogonadism. No neurological signal to the ovary occurs resulting in no estrogen production or ovulation. Pituitary FSH levels are usually low or normal, prolactin levels are normal, and there is no evidence of a tumor. This problem is usually caused by stress, endurance exercise, or anorexia. The latter may manifest in the female athlete triad of eating disorder, amenorrhea, and osteoporosis due to estrogen deficiency. HD is a diagnosis of exclusion following a normal evaluation including a pituitary MRI.
WHO Group II is due to pituitary dysfunction resulting in estrogen production and normal FSH and prolactin levels. The most common presentation is the Polycystic Ovarian Syndrome (PCOS), a prevalent hormonal imbalance affecting 5 – 10% of all reproductive aged women. A 2003 consensus conference in Rotterdam developed criteria to diagnosis PCOS based on a patient having two of the three following signs: ovulatory dysfunction; evidence of elevated androgens (clinical or laboratory); or polycystic appearing ovaries on sonogram. PCOS is diagnosed after other related disorders are excluded (late-onset adrenal hyperplasia, androgen tumor, hyperprolactinemia, and Cushing’s syndrome). Additional features of PCOS include impaired glucose tolerance, elevated BMI, and the metabolic syndrome.