Correlation of serum inhibin concentrations with results in an ovarian hyperstimulation program

In order to appraise follicular development, human serum inhibin was measured daily by radioimmunoassay in 18 women undergoing ovarian hyperstimulation. Serum inhibin in the early follicular phase correlated with the number of follicles greater than or equal to 17 mm in diameter (r = 0.57, n = 18, P less than 0.05), follicles greater than or equal to 14 mm in diameter (r = 0.67, n = 18, P less than 0.01) on the day of human chorionic gonadotropin (hCG) administration and the number of oocytes retrieved (r = 0.67, n = 15, P less than 0.01). The number of oocytes retrieved showed a significant correlation with serum inhibin level on the day of hCG administration (r = 0.84, n = 15, P less than 0.001). These data suggest that: (1) In the early follicular phase, serum inhibin may be a valid index to predict ensuing follicular growth; (2) In the preovulatory phase, serum inhibin may be one of applicable indexes of follicular development during the hyperstimulation cycle.