The diagnostic value of inhibin in infertility evaluation

The fertility patient is entitled to a rapid and accurate diagnosis, a realistic assessment of the prospects for achieving pregnancy, and the timely initiation of an appropriate and effective therapy. The evaluation of ovarian reserve prior to initiation of ovarian stimulation is an important aspect of the infertility work-up of a woman requiring assisted reproductive techniques (ARTs). The ability of the ovary to respond to gonadotropin stimulation by the recruitment of a cohort of follicles is central to the success of treatment such as in vitro fertilization and intracytoplasmic sperm injection. Ovarian dysfunction, often age related, is an increasingly common cause of subfertility, and hyper- and hypogonadotropic dysovulation as well as the commoner polycystic ovarian syndrome (PCOS) are frequently encountered in fertility clinic. In cases of male-factor infertility, an ability to identify an accurate serum marker of Sertoli cell function has enhanced the diagnostic process, as previous endocrine markers such as follicle-stimulating hormone and testosterone were poor correlates of spermatogenic potential. The identification, purification, and cloning of the members of the inhibin-activin superfamily and the subsequent development of sensitive and highly specific two-site enzyme-linked immunoassays for these polypeptide hormones have provided tentative answers to many of the outstanding questions concerning the regulation of the hypothalamo-pituitary-gonadal axis. Assessment of serum levels of inhibin B appears to offer useful prognostic information about ovulatory function and predictive information about response to treatment. During very early pregnancy, especially in the presence of complications associated with ART such as multiple gestation and ovarian hyperstimulation syndrome, measurement of maternal levels of inhibin A and pro-alphaC offers a noninvasive test that can aid the counseling and management of patients.