Prolactin response after gonadotropin-releasing hormone in the polycystic ovary syndrome.

The administration of gonadotropin-releasing hormone (GnRH) has been shown to stimulate prolactin (PRL) release under certain conditions. The authors compared PRL responses after GnRH in normoprolactinemic patients with the polycystic ovary syndrome (PCO) with those of normal ovulatory women in the follicular phase. Seven of 15 patients had a significant increase in PRL after GnRH, whereas none of the control subjects had a positive response. After 1 week of oral L-dopa, the responders no longer exhibited this positive response. Baseline PRL levels in responding patients with PCO were similar to levels in control subjects, whereas nonresponding patients with PCO had higher PRL levels. Baseline follicle-stimulating hormone (FSH)/luteinizing hormone (LH) ratios were higher in patients with a positive response. The positive PRL response after GnRH was not correlated with baseline serum LH, the LH/FSH ratio, delta maximum LH responses, serum testosterone (T), unbound T, or baseline PRL. The positive response correlated positively with serum levels of unbound estradiol (P less than 0.05) and serum unbound estradiol/unbound T ratios (P less than 0.01). These data suggest that under certain conditions a subgroup of patients with PCO may demonstrate a positive PRL response after GnRH. Dopamine, gonadotropins, and estrogen may play a role in this interaction.