Delayed pituitary hormone response to LRF and TRF in patients with anorexia nervosa and with secondary amenorrhea associated with simple weight loss

The qualitative and quantitative responses of LRF-induced LH and FSH release and TRF-induced TSH and Prolactin (PRL) release were evaluated in 21 patients with anorexia nervosa, 19 patients with secondary amenorrhea associated with simple weight loss (SWL) who did not fulfill the psychologic criteria for anorexia nervosa, and 7 normal women in the early follicular phase of the menstrual cycle. Basal plasma LH and FSH were significantly lower in the anorexia nervosa group compared to the SWL group and normals (P < 0.05). The LRF-induced integrated LH responses, however, were the same in the 3 groups and the integrated FSH responses were greater in the underweight groups when compared to normal. The time of the peak LH response (mean ± SE) was significantly delayed (P < 0.01) in both the anorexia nervosa (49 ±6.1 min) and SWL (28 ± 2.5 min) groups when compared to normal (17 ± 2.3 min). The time of the FSH response was significantly delayed (P < 0.05) in anorexia nervosa (95 ± 9.6 min) when compared to normals (35 ± 7.9 min) and SWL patients (62 ± 11.7 min). Normal basal TSH and PRL and normal peak TSH and PRL responses to TRF were found in anorexia nervosa. The time of the TSH and PRL peak (56 ± 8.9 and 36 ± 3.6 min, respectively) in anorexia nervosa was significantly later than normal (26 ± 1.7 and 36 ± 3.6 min, respectively) (P < 0.01). It is concluded that despite normal quantitative response to releasing hormones, there are abnormally delayed responses in both anorexia nervosa and SWL patients. The SWL responses were intermediate between those of the anorexia nervosa group and normals. The constellation of normal quantitative but abnormal kinetic LRF and TRF responses supports the hypothesis that the endocrine changes seen in anorexia nervosa are consistent with hypothalamic dysfunction.