Effect of gonadotrophin-releasing hormone analogue (GnRH-A) administration on serum gonadotrophin and steroid levels in patients with polycystic ovarian disease

A gonadotrophin-releasing hormone (GnRH) analogue, D-Ser[TBU]LRH-EA10, (GnRH-A), at a dose of 200 micrograms was given daily for 2 months to 6 women with polycystic ovarian disease (PCO). Prior to therapy the patients presented elevated LH, testosterone (T), oestrone (E1) and dihydrotestosterone (DHT) in the circulation. In response to GnRH-A, these subjects exhibited a marked decrease in circulating T, DHT and androstenedione (A) levels as measured 24 h after GnRH-A injection, by 4 weeks and onwards (P less than 0.05). After 2 weeks of daily administration, the serum LH profile, evaluated by sampling at 2, 4, 7 and 24 h after injection of GnRH-A, was not different from baseline, whereas after 4, 6 and 8 weeks the levels were significantly lower (*P less than 0.01). The profile of serum T levels was unmodified at the second week, but significantly decreased thereafter (*P less than 0.01). At the end of treatment, the E1 concentrations, elevated in pre-injection condition, were markedly decreased. These data demonstrate that in PCO subjects, GnRH-A significantly lowered the elevated levels of androgens commonly found in these patients. The close correlation observed between reduced serum LH and androgen concentrations suggests that pituitary desensitization could be responsible for the reduction in androgen levels, and may be evidence for a gonadotrophin dependence of the elevated concentrations of T in these patients.