Increased luteinizing hormone pulse frequency in obese oligomenorrheic girls with no evidence of hyperandrogenism.

OBJECTIVE

To determine whether obese, nonhirsute adolescents with oligomenorrhea exhibit similar increased LH pulse secretion patterns compared with obese girls with polycystic ovary syndrome (PCOS).

DESIGN

Prospective, observational study.

SETTING

Tertiary university hospital.

PATIENT(S): Nine obese girls with oligomenorrhea, 15 with PCOS, and 10 controls.

INTERVENTION(S): Twenty-four-hour IV blood sampling for LH (every 10 minutes); measurement of steroid hormones (every 12 hours); and injection of leuprolide acetate (10 microgm/kg SC).

MAIN OUTCOME MEASURE(S): Twenty-four-hour, wake, and sleep LH mean serum concentration, pulse frequency, amplitude; steroid hormones, including free androgen index (FAI); and pre- and post-leuprolide acetate 17-hydroxyprogesterone measurements.

RESULT(S): Twenty-four-hour LH pulse frequency in oligomenorrheic girls (18.6 +/- 1.2) (mean +/- SE) was comparable to that in girls with PCOS (20.9 +/- 0.7) and greater than in normal girls (13.4 +/- 0.8). The pulse number during both sleep and wake was identical in oligomenorrheic and PCOS girls and significantly greater than that of normal girls. Mean 24-hour LH level, serum androgen levels, and FAI in oligomenorrheic girls were equivalent to those of normal controls and lower than those of PCOS girls.

CONCLUSION(S): These preliminary results indicate that obese girls with oligomenorrhea exhibit increased LH pulse frequency in the absence of clinical and/or biochemical evidence of hyperandrogenism.