Assessment of the negative and positive feedback effects of administered oestrogen on gonadotrophin release in patients with anorexia nervosa

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Abstract
Synopsis The capacity of the hypothalamic–pituitary axis to respond with changes in LH release to the negative and positive feedback effects of oestrogen was assessed in 19 patients with anorexia nervosa at different stages of the illness. Ethinyl oestradiol, 200 μg daily for 3 days, was administered and serial estimations of serum LH were carried out during and after the course of oestrogen. In patients with anorexia nervosa tested when markedly underweight, negative feedback effects of oestrogen were demonstrated in those patients with detectable levels of LH. None of the patients demonstrated positive feedback release of LH to the oestrogen stimulus. After the resumption of a more normal weight, basal LH levels were higher and negative feedback effects of oestrogen were observed in 11 out of 12 patients. The complete response to oestrogen with a subsequent positive release of LH to the oestrogen stimulus was shown by only 3 patients. Two of these 3 patients maintained a normal weight during the subsequent 6 months and both resumed regular menstruation shortly after the test. Three additional patients who had shown only negative feedback effects of oestrogen on LH release similarly maintained a normal weight and only 1 of them resumed menstruation, starting 3 months after the oestrogen test. It was concluded that in recovery from anorexia nervosa there is a return of normal hypothalamicpituitary–gonadal activity in a definite sequence with recovery of the hypothalamus to respond normally to the negative feedback effects of oestrogen followed by return of the positive feedback capacity between oestrogen and LH which allows menstruation to resume. The resumption of normal hypothalamic–pituitary function is clearly dependent in part upon correction of the malnutrition. However, after correction of the malnutrition some patients fail to menstruate, and this appears to be determined by a continuing impairment of the hypothalamus to respond normally to the feedback effects of oestrogen upon gonadotrophin release.