Hypothalamic-pituitary-gonadal function in anorexia nervosa and bulimia

Patients with anorexia nervosa (AN) exhibit neuroendocrine abnormalities that may result solely from emaciation or may reflect defective endocrine mechanisms which are intrinsic to disordered eating even in the absence of starvation. To distinguish these possibilities, we have studied indices of hypothalamic-pituitary-gonadal (HPG) function in 9 patients with AN, 12 normal weight patients with bulimia and recent or current oligomenorrhea, and 8 normal weight controls. Measurement of 24-hour luteinizing hormone (LH) secretion with 30-min sampling revealed significantly fewer LH secretory spikes and a trend toward lower mean 24-hour LH levels in both bulimic and anorectic patients than in controls. Stimulation with gonadotropin releasing hormone produced elevated LH responses in the bulimic group and blunted LH responses in the anorectic group. Stimulation with estradiol revealed diminished LH augmentative responses and a trend toward diminished follicle stimulating hormone augmentative responses among bulimic as well as AN patients compared to controls. In each instance, the bulimic group tended to show within-group heterogeneity, with some individuals falling within the AN range. These findings suggest that HPG axis abnormalities in eating disordered patients cannot entirely be attributed to emaciation and that factors other than subnormal weight contribute to disturbed hypothalamic-pituitary functioning in these patients.