Relative bioactivity of endogenous luteinizing hormone during superovulation therapy for in vitro fertilization in normal-cycling women.

PURPOSE

Impaired outcome of in vitro fertilization treatment has been related to abnormal luteining hormone (LH) secretion and to the occurrence of a premature LH surge. The purpose of this study was to compare LH serum concentrations, measured by bioassay (LH-b) and immunoassay (LH-i), during early and late follicular phases in normal-ovulatory women who were stimulated with clomiphene, human menopausal gonadotropin (HMG), and human chorionic gonadotropin (hCG), while undergoing in vitro fertilization (IVF) treatment for infertility, due mainly to tubal damage.

RESULTS

Of 22 patients, 15 had an LH surge (surge group) before receiving hCG and 7 did not (nonsurge group). LH-b and LH-i concentrations were higher in the late follicular phase than before clomiphene treatment, but the LH-b/LH-i (B/I) ratios remained unchanged and there were no significant differences between the LH surge and the nonsurge groups. In the surge group, the B/I ratio appeared to fall during the LH surge [presurge values, 5.4 +/- 0.5 (SD) and 5.2 +/- 0.5; surge values, 4.9 +/- 0.6 and later 4.0 +/- 0.6], but the differences were not significant, and in some individuals, the B/I ratio later rose as the LH surge progressed.

CONCLUSIONS

Our findings suggest that interference with IVF outcome by a spontaneous LH surge is due to quantitative and/or exposure time effects on the oocyte, rather than to any qualitative variation in bioactivity of LH.