In the present study, we investigated the endocrine status of patients with anorexia nervosa during weight loss (WL), as well as, after weight recovery (WR). A comparison between our findings and those obtained from other populations previously described was made. We studied 12 female patients during WL; 7 of them were reevaluated after WR. Stimulation tests with LRH, TRH, ACTH and insulin-induced hypoglycemia were performed in all cases. During the WL phase, basal serum levels of LH and estradiol, as well as the LH response to LRH, were diminished in comparison with normal values. Basal serum levels of FSH were low or normal. The function of the hypothalamic pituitary-ovarian axis was recovered in all patients restudied; six out of seven returned to ovulation within the first 4 months after WR. The remaining patient presented hypothalamic amenorrhea because of excessive physical activity. Four patients exhibited basal low T3 and T4 levels with normal TSH and a retarded response to TRH during WL. At WR some patients completely recovered their thyroid function while others developed clinical hypothyroidism. Six months after WR all patients were euthyroid. Prolactin response to TRH was unaffected in 10 patients. One patient had basal hyperprolactinemia and hyperesponsiveness to TRH, and the remaining one had only a PRL hyperesponsiveness; this latter finding persisted in one of these patients during the WR phase. This abnormality was attributed to changes in the dopaminergic tone secondary to stress. Although serum growth hormone concentrations were normal in all patients during WL, two of them had basal hypersecretion and hyperesponsiveness to hypoglycemia during WR, which was attributed to protein deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)