MODULATORY ROLE OF ESTROGENS AND PROGESTINS ON GROWTH-HORMONE EPISODIC RELEASE IN WOMEN WITH HYPOTHALAMIC AMENORRHEA

Objective: To define the characteristics of spontaneous GH episodic se cretion and the modulatory role of gonadal steroids in patients with h ypothalamic amenorrhea associated with weight loss. Design: Women were studied for 8 hours, sampling every 10 minutes, and plasma GH levels were measured by RIA. Subjects: Fifteen patients with weight-loss-rela ted amenorrhea were studied in baseline conditions. Five out of 15 pat ients underwent two cycles of hormonal replacement therapy with E2 pat ches (100 mug every 3 days for 24 days) and medroxyprogesterone acetat e (MPA) (10 mg/d, from day 12 to day 24). On the second cycle of thera py, the pulsatility study was repeated twice: after only estrogen (day 11) and after E2 plus progestin (day 22). Four normally cycling women were studied as a reference group during midfollicular and midluteal phases. Results: Amenorrheic patients showed mean plasma GH levels sim ilar to healthy women during the follicular phase but significantly lo wer than those observed during the luteal phase. GH pulse frequency wa s higher in patients than in controls, whereas pulse amplitude was com parable with the follicular phase but lower during the luteal phase. D uring the hormonal replacement therapy, when only E2 was administered, GH pulse frequency decreased, whereas GH integrated plasma concentrat ions and GH pulse amplitude increased significantly. After MPA and E2 administration, GH pulse amplitude and GH plasma levels decreased, whi ch was similar to pretreatment condition. Conclusions: The present stu dy demonstrated that in amenorrhea associated with weight loss the fre quency of GH episodic release is significantly higher than in normally cycling women. Moreover, a different modulatory role of estrogen (inc reased amplitude) and P (decreased amplitude) on the episodic release of GH in amenorrheic women undergoing a replacement treatment was show n by the present data.