Blunted growth hormone responses to clonidine in adolescent girls with early anorexia nervosa. Evidence for an early hypothalamic defect.

We studied growth hormone (GH) levels in 14 adolescents with anorexia nervosa (AN), 12-20 years of age. All had amenorrhea and the duration of symptoms ranged from 2-24 months. There was no difference in unstimulated GH between the girls with AN and endocrinologically normal girls. However, the GH response to the alpha-adrenergic agent clonidine was blunted (less than 10 ng/ml) in 11 of 14 girls with AN. Our results of a normal basal GH level and blunted response to stimulation is in contrast to some reports of high basal GH levels and an exaggerated response to pituitary stimulation although it agrees with other studies. Our patient population was younger and at an earlier stage of the disease (12 with symptoms for less than 1 year) than the AN patients previously reported to have elevated GH secretion. In view of studies that report an elevated GH response to growth hormone releasing factor, our results suggest that the AN patient's abnormalities in GH secretion may result from an abnormal hypothalamic response to adrenergic stimuli. This hypothalamic abnormality might also contribute to the growth failure seen in adolescent girls with AN.