Amenorrhea is simply a medical term defined as the absence of menses in a post-pubescent woman of reproductive age. Amenorrhea may be defined as either primary or secondary: in primary amenorrhea menses does not occur by the age of 16 in the presence of normal growth and secondary sexual characteristics while in secondary amenorrhea menstruation ceases after menarche.
There is no consensus definition as to when secondary amenorrhea begins, but in practical terms if a period has not occurred in over 90 days, medical attention should be sought. Both primary and secondary amenorrhea may occur as a result of eating disorders but secondary amenorrhea is by far more commonly seen.
Secondary Amenorrhea Caused by Eating Disorders
The type of secondary amenorrhea caused by eating disorders is termed functional hypothalamic amenorrhea. Although restrictive eating disorders or excessive exercise that lead to low body weight may result in primary amenorrhea if they exist prior to puberty, they usually shut down normal hypothalamic function after the onset of puberty.
Up to 20% of Bulimics may experience amenorrhea while between 5% and 44% of Anorexics experience amenorrhea. People diagnosed with an Eating Disorder Not Otherwise Specified (EDNOS), Compulsive Exercise, or the Female Athlete Triad, may also experience amenorrhea. Eating disorders associated with a high body weight such as Binge Eating Disorder are not associated with amenorrhea. The presence of amenorrhea is, however, one of the criteria necessary to achieve a diagnosis of Anorexia Nervosa according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM IV).
Amenorrhea from Eating Disorders - Hormonal Interruption
When a person engages in excessive exercise or disordered eating that results in low body fat and low body weight the normal secretion of Gonadotropin Releasing Hormone (GnRH) from the hypothalamus is interrupted. This leads to disordered secretion of both Follicular Stimulating Hormone (FSH) and Leutenizing Hormone (LH) which are essential to the normal menstrual cycle and ovulation. A critical level of body fat must be present for normal GnRH, LH, and FSH secretion and subsequent menstruation.
Though often reversible and not a medical danger in and of itself, the type of secondary functional hypothalamic amenorrhea associated with eating disorders may result in complications. Both infertility and osteoporosis may occur after prolonged functional hypothalamic amenorrhea.
Treatment for the type of secondary amenorrhea associated with eating disorders requires treatment of the primary cause. Restoring normal body weight is the first course of action. Hormonal therapy may be required in resistant cases.