Response to clomiphene citrate challenge test in normal women through perimenopause.

Objective: To identify the physiological changes that discriminate subgroups of women along the reproductive continuum.

Methods: This prospective study was carried out at the outpatient facility of George Washington University Medical Center and the outpatient clinic of the National Institutes of Health Clinical Center. Twenty-five female subjects were divided into 4 biologically distinct groups: group 1 (n = 4) regular menstrual cycles and under age 35; group 2 (n = 11) regular cycles and over age 35; group 3(n = 6) irregular cycles and over age 35, and group 4(n = 4) menopausal. Measurements of basal and stimulated gonadotropins (immunoactive LH, LH-I; bioactive LH, LH-B; immunoactive FSH, FSH-I) and E2 were obtained before and after administration of clomiphene citrate. Basal and stimulated gonadotropins and E2 were analyzed to discriminate between subject groups 1-4. The relationship of menstrual cyclicity to hormone levels was evaluated.

Results: Basal levels of LH-I, LH-B, FSH-I could discriminate only group 4 vs. groups 1-3. Stimulated levels of FSH-I and E2 were significantly different for group 2 vs. 3 and group 2 vs. 4. Group 1 was similar to group 2. Both stimulated FSH-I and stimulated LH-I and LH-B differentiated group 4 vs. groups 1-3. The LH-B:LH-I (B:I) ratio was not discriminatory after the clomiphene citrate challenge test (CCCT).

Conclusions: Baseline hormone values were useful in distinguishing only group 4. CCCT unmasked differences in FSH and E2 between irregularly and regularly cycling older women; these differences were not scen with LH-B or B:I ratio. Stimulated FSH was the most useful hormone parameter and paralleled menstrual cycle regularity as a useful discriminator in older women.