Inhibin A ELISA Test

Inhibins are secreted by ovarian granulosa cells in females and by testicular Sertoli cells in males [1]. Both inhibin A and inhibin B are produced in females, but in males inhibin B is the major circulating inhibin.

During the menstrual cycle and early pregnancy, inhibin A is produced by the corpus luteum [1]. At the onset of menstruation during the early follicular phase, very low levels of inhibin A are found [2]. Levels increase dramatically in the late follicular phase and maximize in the mid-luteal phase [2]. During pregnancy, inhibin A levels in maternal serum are considerably higher. Maternal serum levels of inhibin A increase during the first trimester and decline after about 10 weeks. Levels remain stable at 15 to 25 weeks and then increase, reaching peak at term [1]. In pregnancy, inhibin A production occurs at a number of sites, including the fetus, placental and fetal membranes, and the ovary [3]. The feto-placental unit appears to be the major source of increased circulating concentrations of inhibin A in early pregnancy [4]. Although the function of inhibin A in pregnancy is unknown, inhibin A may be involved in fetal and placental development [3].

1. Wald NJ, et al. Prenat Diag 16: 143-153, 1996.
2. Groome N, et al. Clin Endocrinol 40: 717-723, 1994.
3. Riley SC, et al. Hum Reprod 11: 2772-2776, 1996.