Pituitary function is altered during the same cycle in women with polycystic ovary syndrome treated with continuous or cyclic oral contraceptives or a gonadotropin-releasing hormone agonist.

OBJECTIVE

To determine if continuous oral contraceptive (OC) therapy was superior to a cyclic regimen in achieving persistent pituitary suppression of LH in patients with polycystic ovary syndrome (PCOS).

DESIGN

Fourteen women (ages 16 to 41 years) with PCOS received one of three treatment groups: continuous OC therapy (30 micrograms ethinyl E2 plus 150 micrograms desogestrel), cyclic OC therapy, or monthly injections of a GnRH agonist (GnRH-a, leuprolide acetate depot 3.75 mg) for 3 months. Basal hormone levels were obtained before initiating therapy, on days 15 to 17 of the 3rd month of treatment (study 1) and again on days 26 to 28 of the 3rd month (study 2). A GnRH stimulation test was also performed during study 1 and study 2.

RESULTS

After 3 months of treatment, LH levels were decreased significantly in all groups with less effective suppression observed in the cyclic OC group compared with the continuous OC or GnRH-a groups. A significant rise in LH was found only in the cyclic OC group after 5 to 7 days of placebo treatment (study 1 versus study 2). An increase in T was also observed in the cyclic OC group during study 2, whereas the continuous OC and GnRH-a groups showed continued inhibition of T levels. Although there was no significant difference in LH area under the curve (AUC) measurements after GnRH stimulation in study 1 versus study 2, the LH AUC was significantly greater in both studies in the cyclic OC group compared with the continuous OC or GnRH-a groups.

CONCLUSIONS

Increased LH secretion during the week of placebo in the cyclic OC group was associated with a concomitant increase in T. The striking rise in LH secretion after GnRH stimulation in the cyclic OC group may represent increased pituitary sensitivity in patients receiving cyclic OCs regardless of the phase of the treatment cycle, perhaps secondary to increased pituitary stores of LH in these women.