Are there ethnic differences in granulosa cell function?

Abstract

We recently reported that Asian patients undergoing IVF have higher serum estradiol levels (peak and per oocyte) when compared to their Caucasian counterparts. We also observed this difference within a population of anonymous oocyte donors: Asian oocyte donors demonstrate 23% higher peak estradiol levels (P=0.0037) and 22% higher estradiol per oocyte (P=0.02) compared to Caucasian donors during gonadotropin stimulation (ASRM, 2006). The physiologic mechanism that explains this difference is not known, although altered estradiol metabolism may be suggested. The object of this study is to determine if follicular fluid estradiol levels differ between Asians and Caucasians. This finding would suggest altered granulosa cell production of estradiol as a possible mechanism for the increased serum levels. Prospective Cohort. A power analysis indicated that a total of 240 Caucasian and 100 Asian infertility patients are necessary in order to observe a 20% difference (100 ng/dl) in follicular estradiol, consistent with serum differences noted above. Patient ethnicity was defined by self report. Follicles were individually collected during transvaginal aspiration. After removal of the oocyte, follicular fluid was analyzed for estradiol. Follicles yielding >2 mls of fluid (>16 mm size) were included for analysis. Analysis was performed with Student's t-test.Tabled 1Table.Mean Follicular Estradiol (Mean ± SD)Min-MaxAsian555 ± 316(14–1492)Caucasian504 ± 323(55–1372)Two tailed P-value = 0.32. Open table in a new tab Two tailed P-value = 0.32. A total of 109 follicles were analyzed from 70 Caucasian patients and a total of 59 follicles were analyzed from 50 Asian patients. Preliminary results indicate Asian patients have 9% higher follicular estradiol levels, though this difference does not reach statistical significance (Table). Data collection is on-going in order to achieve power calculation estimates. The higher serum estradiol levels in Asians undergoing stimulation for IVF remains unexplained at the physiologic level. Preliminary data indicates a non-significant increase in follicular estradiol in Asians compared to Caucasian. Should on-going data collection allow us to confirm the observed elevation in estradiol levels, then additional investigation regarding granulosa cell function will be warranted. Ultimately, an improved understanding of differences in reproductive physiology across ethnicities is critical for tailoring and optimizing diagnostic and treatment strategies.