Clinical evidence for an LH 'ceiling' effect induced by administration of recombinant human LH during the late follicular phase of stimulated cycles in World Health Organization type I and type II anovulation.

BACKGROUND The objective of these studies was to test the hypothesis that over-dosing with recombinant human LH (rLH) during the late follicular phase would suppress the development of follicles. METHODS Two double-blind studies were conducted. In study A, WHO I anovulatory patients received treatment with rFSH and rLH. When at least one follicle reached a mean diameter of 10-13 mm, patients were randomized using a computer-generated randomization list (stratified by centre) to rFSH and rLH (225 IU/day) (n = 8) or rLH alone (n = 6) or rFSH alone (n = 6). In study B, WHO II anovulatory patients with a hyper-responsive FSH were randomized to rLH (225 IU/day) (n = 4) or rLH 450 IU/day (n = 8) or placebo (n = 5). RESULTS Study A: the mean number of follicles >/=11 mm was 4.2 +/- 0.3 in the rFSH group, 1.5 +/- 0.7 in the rLH group and 6.0 +/- 2.3 in the rFSH/rLH group (P = 0.07). 0/8 patients presented follicular growth arrest in the rFSH group, but 4/6 in the rLH group and 1/6 in the rFSH/rLH did. Study B: 5/12 patients presented follicular growth arrest in the rLH groups, but none in the placebo group. The mean number of follicles >/=11 mm was 4.6 +/- 1.8 for the placebo group, 2.5 +/- 1.9 for the rLH 225 IU group and 4.2 +/- 1.4 in the rLH 450 IU group (not significant). CONCLUSIONS Results of this pilot study suggest that rLH alone can trigger follicular growth arrest in a significant number of patients, suggesting the existence of an 'LH ceiling' during late follicular maturation.