Pituitary response to bolus and continuous intravenous infusion of luteinizing hormone-releasing factor in normal women and women with polycystic ovarian syndrome

Plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were measured in response to luteinizing hormone-releasing factor (LRF), given as a 100 μg intravenous bolus and/or as a 4 hour infusion of 0.2 μg per minute to 27 normal menstruating women and 15 women with the polycystic ovarian syndrome (PCOS). In PCOS, LH response to bolus LRF was significantly greater than those of normal women at days 1 to 4 and 8 to 10 of the cycle, whereas FSH responses were similar in all women studied. Continuous LRF infusion resulted in a biphasic LH release pattern. In normal women, the early phase was low until days 12 to 14 of the normal cycle, whereas the second phase rose progressively from the early follicular to the periovulatory period. In PCOS, the early phase was relatively large and qualitatively resembled the normal periovulatory pattern. The increased pituitary LH response to LRF in PCOS is associated with a relatively large early releasable LH pool and a low FSH response.