An evaluation of the serum FSH as a biomarker for ovarian toxicity in the rat

There is a need for a biomarker to evaluate numbers of oocytes in an ovary exposed to various exogenous toxicants. Experiments that had been previously reported were reviewed to assess the serum FSH as such a biomarker. Rats that had been exposed to direct ovarian radiation and direct ovarian radiation with cyclophosphamide were reviewed to ascertain the relationship of follicle numbers to the serum FSH. Under the conditions of reduced serum estrogen, linear regression analysis indicated that the serum FSH correlated best with the calculated volume of antral follicles. Receiver operating characteristic curves were calculated to determine that an elevation of the serum FSH two standard deviations above the mean had the greatest diagnostic power in predicting a significant loss in both the number of healthy follicles and the calculated volume of healthy antral follicles. The serum FSH as a biomarker appears to have utility as a measure of the ovarian content of healthy antral follicles rather than as a measure of the total number of oocytes alone.