We tested hypothalamic, pituitary and endocrine function in 19 patients with secondary amenorrhea associated with simple weight loss who did not have anorexia nervosa to evaluate the effects of weight loss on these systems. Thermoregulation at 10°C and 49°C was abnormal and correlated with the percentage below ideal body weight (r = 0.62, P<0.02, and r = 0.55, P<0.05, respectively). Partial diabetes insipidus was found in 27 per cent of patients with simple weight loss. They had delayed peak plasma luteinizing hormone levels after 10 μg of luteinizing-hormone-releasing factor, which was correlated with percentage below ideal body weight (r = 0.49, P<0.05). Delayed peak plasma thyrotropin levels after 500 μg of thyrotropin-releasing factor were found. No prolactin, pituitary, thyroid or adrenal abnormalities were present. These findings are qualitatively similar to results of studies in 29 patients with anorexia nervosa, but less severe and less frequently present. We conclude that hypothalamic dysfunction may be caused by weight loss per se. (N Engl J Med 297:1141–1145, 1977) Anorexia nervosa is a disorder of unknown cause, presenting as extreme weight loss associated with abnormal ideation about food and body image.1 It is associated with numerous abnormalities of endocrine and hypothalamic function.2 3 4 5 6 7 8 9 10 Whether or not these dysfunctions are secondary to weight loss, per se, or are part of a syndrome of primary hypothalamic disease is unclear. To clarify these and other issues about the effects of weight loss on hypothalamic and endocrine function, we studied patients with secondary amenorrhea associated with simple weight loss and compared them to patients with anorexia nervosa and to normal women. Patients and Methods.
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