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Disorders of Menstruation

SECONDARY AMENORRHEA

Secondary amenorrhea can result from dysfunction of the central nervous system, pituitary gland, thyroid gland, adrenal gland, ovary, or uterus or from disorders of peripheral metabolism (see the box). The most common cause of secondary amenorrhea is the development of chronic hypothalamic anovulation, which can be induced by stress, increased exercise levels, a precipitous decrease in body weight, or the development of an inappropriate ratio of lean body mass to fat. If pregnancy is ruled out, the patient with chronic hypothalamic anovulation is found to have normal gonadotropin levels with an appropriate ratio of LH to FSH and will respond with withdrawal to a progestogen challenge abnormal vaginal bleeding. Any of the aforementioned states carried to the extreme form, however, result in hypothalamic amenorrhea with a fall in LH and FSH levels, inversion of the LH-to-FSH ratio, and failure to respond to progestogen challenge. Other conditions may mimic these findings, including systemic illnesses that generally present as hypogonadotropism; head trauma; space-occupying lesions of the central nervous system; and the intake of numerous pharmaceutical agents--most notably minor tranquilizers, monamine oxidase inhibitors, and drugs that alter serotonin metabolism. Unusual space-occupying lesions such as fibromas from neurofibromatosis, infiltrative disorders such as his-tiocytosis X (Hand-Schiiller-Christian syndrome), and syphilis and tuberculosis, which can form granulomas, also result in amenorrhea. Rare causes of amenorrhea include its association with temporal arteritis or cavernous sinus thrombosis amenorea disfunctional

Pituitary dysfunction can likewise result in secondary amenorrhea. Perhaps the most common cause is functional hyperprolactinemia, which is thought by many investigators to represent a disorder of central dopamine metabolism or to indicate the presence of prolactinomas. Hyperprolactinemia is diagnosed by elevated prolactin levels on multiple occasions. Likewise, secondary amenor-rhea can occur after resection of prolactinomas or other tumors, or it can occur in association with infarction of the pituitary gland (Sheehan's syndrome) or head trauma. Hypopituitarism is diagnosed by the finding of low-nor-mal gonadotropin levels. Hypothalamic dysfunction can be differentiated from a pituitary disorder by using a

Hypothyroidism can at times result in menstrual dysfunction and may or may not be associated with hyperprolactin-emia. The patient with hypothyroidism may present with dry skin, lethargy, and constipation. Frequently the T4 level will be normal, whereas the TSH level will be markedly

elevated. At times, secondary hypothyroidism will be detected with a low T4 level and low TSH level. All of these conditions are treated with replacement thyroid hormones.

Disorders of adrenal metabolism likewise can result in the development of secondary amenorrhea. Dehydroepi-androsterone sulfate may be mildly elevated in patients with polycystic ovary syndrome (PCOS) 50% of the time or in patients with variations of congenital adrenal hyper-plasia. Levels of DHEAS may be markedly elevated and associated with virilism in patients with adrenal adenomas and other tumors. This elevation may be corticotropin dependent or independent and is best evaluated by a 24-hour urine measurement of free cortisol. Interpretation of the 24-hour urine measurement is based on knowledge of the patient's creatinine clearance periods dysfunctional uterine bleeding .

Obesity is associated with the development of