Bulimia Nervosa
Just as the diagnostic criteria for anorexia have been redefined over the years, so too have the criteria for bulimia. The current diagnostic criteria are detailed in Table 2.4 Whereas the prominent features of anorexia are the caloric restriction and resulting underweight, the prominent elements of bulimia are episodes of binge eating (large amounts of food with a lack of control) and the compensatory behaviors that follow, in a patient who is either normal weight or overweight. The compensatory behaviors include self-induced vomiting, abuse of laxatives and diuretics, over-exercise, caloric restriction and abuse of diet pills. Usually the patient suffers painful remorse after the behaviors but is unable to control the impulse to repeat them. The young woman with bulimia characteristically has low self-esteem, is depressed and/or anxious, and has poor impulse control. She typically engages in other risky behaviors, such as substance abuse, unprotected sexual activity, self-mutilation and suicide attempts.
TABLE 2
Diagnostic Criteria for Bulimia Nervosa --------------------------------------------------------------------------------
Recurrent episodes of binge eating. An episode of binge eating is characterized by both of the following:
eating, in a discrete period of time (e.g., within any two-hour period), an amount of food that is definitely larger than most people would eat during a similar period of time and under similar circumstances
a sense of lack of control over eating during the episode (e.g., a feeling that one cannot stop eating or control what or how much one is eating)
Recurrent inappropriate compensatory behavior in order to prevent weight gain, such as self-induced vomiting; misuse of laxatives, diuretics, enemas or other medications; fasting; or excessive exercise.
Binge eating and inappropriate compensatory behaviors both occur, on average, at least twice a week for three months.
Self-evaluation is unduly influenced by body shape and weight.
Disturbance does not occur exclusively during episodes of anorexia nervosa.
Specify type:
Purging type: during the current episode of bulimia nervosa, the person has regularly engaged in self-induced vomiting or the misuse of laxatives, diuretics or enemas
Nonpurging type: during the current episode of bulimia nervosa, the person has used other inappropriate compensatory behaviors, such as fasting or excessive exercise, but has not regularly engaged in self-induced vomiting or the misuse of laxatives, diuretics or enemas
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Reprinted with permission from American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 4th ed. Washington, D.C.: American Psychiatric Association, 1994:549-50. Copyright 1994.
While amenorrhea is a diagnostic criterion for anorexia, menstrual irregularity occurs in only about one half of patients with bulimia, probably because these women rarely achieve underweight when irregularity occurs. The mechanism appears to be related to hypothalamic-pituitary function. One study19 that examined body weight as a predictive factor of abnormal menstruation in patients with bulimia concluded that when current weight was less than 85 percent of a patient's past high weight, abnormal 24-hour secretion of LH is likely. This study followed another study20 that suggested decreased pulsatile LH secretion as a factor. Another very small study21 showed elevated levels of free testosterone in patients with bulimia.
The oligomenorrhea in patients with bulimia does not, however, appear to impact their bone mineral density. According to one study22 that compared patients with anorexia, patients with bulimia and matched control patients, bone mineral density in those patients with bulimia was similar to that in the control patients. Interestingly, this study also showed that weight-bearing exercise had a protective effect in patients with bulimia that did not occur in those with anorexia. Therefore, osteoporosis may not be a concern in patients with bulimia, particularly those who exercise regularly.
If menstrual irregularity occurs in the adolescent with bulimia, a limited evaluation is necessary. After completing a careful history and physical examination, the laboratory work-up depends on the particular pattern seen. If significant oligomenorrhea is reported, it may be helpful to obtain the patient's levels of LH and FSH, thyroid-stimulating hormone, prolactin, and total and free testosterone. If androgenization is present, obtaining a dehydroepiandrosterone sulfate level will help to evaluate adrenal function. If a patient has not menstruated in three months or more, a progesterone challenge test (administration of medroxyprogesterone acetate [Provera] in a dosage of 10 mg daily for seven days) would be indicated. A withdrawal bleed two to seven days after treatment indicates sufficient levels of estrogen. In a chronically anovulatory teenaged patient who is not underweight and who has an elevated androgen level and positive results on the progesterone challenge test, one must assume that the patient has chronically circulating unopposed estrogen. In this situation, it is necessary to induce a withdrawal bleed at least every three months to reduce the risk of endometrial cancer later in life. This is done by repeating progesterone administration every three months or by cycling with combined oral contraceptive pills.