Gonadotropin secretion in bulimia nervosa

Twenty-two normal weight women with bulimia nervosa (BN) were studied (mean age, 25 +/- 5 yr; body mass index, 20.2 +/- 2.6 kg/m2). Sixteen of them reported menstrual cycles in the range of 21-42 days, and 6 had experienced absence of menstruation for at least 3 months. Twenty-one healthy women with regular menstrual cycles (mean age, 23 +/- 2 yr; body mass index, 20.7 +/- 1.4) served as the control subjects. Frequent morning blood samples for estradiol (E2) and progesterone (P4) determinations were obtained for the duration of 1 menstrual cycle or for 6 weeks in the case of amenorrhea. LH, FSH, cortisol, and insulin secretion were studied on day 3, 4, or 5 after the onset of a menstrual cycle or on a random day in the 6 BN women with amenorrhea. Blood samples were collected at 15-min intervals from 1800-0600 h for LH and FSH and at 30-min intervals from 2400-0600 h for cortisol and insulin. Nineteen of the 21 controls, but only 10 of the 22 BN women, fulfilled the following standard criteria: maximum E2 above 440 pmol/L, maximum P4 above 19 nmol/L, and luteal phase length of 9 days or more. The 10 BN women with normal menstrual cycles had lower mean insulin concentrations than the controls (70 +/- 20 vs. 120 +/- 30 pmol/L; P less than 0.01), but gonadotropin secretion, cortisol, and T3 concentrations were similar. The 8 BN women with amenorrhea or ovulatory dysfunction (maximum E2, less than 440 pmol/L; maximum P4, less than 6 nmol/L) displayed decreased mean LH pulse frequency (2.6 +/- 2.4 vs. 5.7 +/- 2.0 pulses/12 h; P less than 0.01), increased mean cortisol (120 +/- 40 vs. 80 +/- 20 nmol/L; P less than 0.01), decreased mean insulin (90 +/- 40 vs. 120 +/- 30 pmol/L; P less than 0.05), and decreased mean T3 concentrations (1.5 +/- 0.3 vs. 1.8 +/- 0.2 nmol/L; P less than 0.01). The data suggest that BN in normal weight women is associated with an increased rate of ovarian dysfunction; decreased pulsatile LH secretion seems to be an important mechanism. Increased cortisol in the disturbed subgroup indicates that activation of the hypothalamic-pituitary-adrenal axis may play a role in the pathogenesis of gonadal dysfunction in bulimia nervosa.