Bioactive LH in women with polycystic ovaries and the effect of gonadotrophin suppression.

Discrepancies between levels of bioactive LH (B-LH) and immunoreactive LH (I-LH) in polycystic ovarian syndrome (PCO) have been reported previously. Serum levels of I-LH, B-LH (by dispersed Leydig cell assay), FSH, oestradiol (E2) and progesterone (Prog) were measured once to three times weekly over 4 weeks in 13 women with classical clinical, ultrasound and endocrine features of PCO. Eleven women attending for infertility but whose profiles when studied three times weekly by combined endocrine and ultrasound assessment were normal and ovulatory served as controls. Seven of the women with PCO were evaluated during and after 3 weeks suppression with ethinyloestradiol (30 micrograms) plus 150 micrograms either of desogestrel or levonorgestrel; two were given both treatments. Both I-LH and B-LH levels were higher in PCO patients (20 +/- SD 5 U/l and 46 +/- 9 U/l respectively, P less than 0.0001), compared with all phases of the normal cycles except the mid-cycle peak. The B-LH to I-LH (B:I LH) ratio in PCO patients (2.5 +/- 0.7) was higher than in all the control cycle phases (P less than 0.05). I-LH, B-LH, B:I LH ratio, FSH and E2 were all suppressed from the second week of oestrogen-progestogen treatment (P less than 0.01) and returned gradually to pretreatment levels by the third or fourth week after suppression. The LH and FSH levels and B:I LH ratio in PCO patients during suppression were comparable with levels in the early and mid-follicular phases of control cycles but the LH/FSH ratio remained significantly raised (P less than 0.01) at 2.3 +/- 0.7.(ABSTRACT TRUNCATED AT 250 WORDS)