Is the inappropriate gonadotropin secretion of patients with polycystic ovary syndrome similar to that of patients with adult-onset congenital adrenal hyperplasia?

OBJECTIVE

To assess gonadotropin alterations in adult-onset congenital adrenal hyperplasia (CAH) and to compare these findings with those of patients with polycystic ovary syndrome (PCOS) in an effort to better understand the pathophysiology of these abnormalities.

DESIGN

Prospective study of 9 newly diagnosed patients with CAH, 10 with PCOS, and 10 ovulatory controls.

INTERVENTIONS

Baseline measurements of serum androgens, progestins, estradiol (E2), estrone (E1), unbound E2, luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Serum LH and FSH were measured after intravenous gonadotropin-releasing hormone (GnRH) and in 15-minute blood samples for 6 hours to determine LH pulsatility.

RESULTS

Serum androgens were elevated but comparable in the two patient groups. Serum LH was also elevated (P less than 0.05) but was higher in PCOS than CAH. Serum LH:FSH ratios were similar as were the responses to GnRH. Serum E1 was elevated only in PCOS, but unbound E2 was elevated to the same degree in both PCOS and CAH (P less than 0.05). Patients with PCOS had a decreased LH interpulse interval compared with controls and CAH (P less than 0.05), but LH pulse amplitude was increased in both PCOS and CAH (P less than 0.05). Serum E2 and unbound E2 correlated significantly with LH (P less than 0.05), LH responses to GnRH as well as to LH pulse amplitude in CAH (P less than 0.05). The LH interpulse interval did not correlate with estrogen in any group. None of the LH parameters correlated with serum progestin levels in CAH.

CONCLUSIONS

The gonadotropin abnormalities of CAH appear to be intermediate between those of controls and PCOS. Although elevated estrogen may explain these abnormalities in CAH, additional factors may be operative in PCOS.