EPISODIC RELEASE OF PROLACTIN IN WOMEN WITH WEIGHT LOSS-RELATED AMENORRHEA

Amenorrhea associated with weight loss is characterized by several neu roendocrine aberrations. The aim of the present study was to define th e characteristics of episodic secretion of prolactin in women with wei ght loss-related amenorrhea. To evaluate whether hypoestrogenism was r esponsible for the changes in prolactin secretion in amenorrheic women , the pulsatile secretory pattern was also studied during hormone repl acement therapy (HRT). Fifteen patients were studied by blood sampling every 10 min for 8 h. Four normally cycling women were studied as a r eference group, during both the midfollicular and midluteal phases. Me an plasma prolactin levels and pulse amplitude were lower in amenorrhe ic patients than in controls. The prolactin pulse frequency was higher than that in controls during the follicular phase, but lower than con trols during the luteal phase of the menstrual cycle. During HRT, mean plasma prolactin levels significantly increased, pulse frequency decr eased and pulse amplitude significantly increased both during estradio l and estradiol plus medroxyprogesterone acetate administration. In co nclusion, in amenorrhea associated with weight loss the chronobiologic al organization of prolactin secretion is deranged, both as a result o f a neuroendocrine alteration and as a result of low plasma levels of gonadal steroids.