Inhibin A and Inhibin B
Inhibin A and inhibin B are hormones made by ovarian follicles. They signal the pituitary gland to lower its output of follicle-stimulating hormone. Inhibin B comes mainly from small growing follicles. Inhibin A comes mainly from the mature follicle and the corpus luteum. In men, inhibin B reports the work of the Sertoli cells that support sperm.1
As a marker of egg count, inhibin B has limits. One study measured it in 58 ovulating women. After a dose of FSH it tracked closely with antral follicle count. Baseline levels generally did not.2
Inhibin also marks the second half of the cycle. Ten women with luteal phase deficiency had lower luteal inhibin, estradiol and progesterone than 28 control women.3
Cited in this entry
- Foresta C, Bettella A, Spolaore D, Merico M, Rossato M, Ferlin A. Suppression of the high endogenous levels of plasma FSH in infertile men are associated with improved Sertoli cell function as reflected by elevated levels of plasma inhibin B. Human reproduction (Oxford, England). 2004. https://pubmed.ncbi.nlm.nih.gov/15117900/
- Yong PY, Baird DT, Thong KJ, McNeilly AS, Anderson RA. Prospective analysis of the relationships between the ovarian follicle cohort and basal FSH concentration, the inhibin response to exogenous FSH and ovarian follicle number at different stages of the normal menstrual cycle and after pituitary down-regulation. Human reproduction (Oxford, England). 2003. https://pubmed.ncbi.nlm.nih.gov/12525438/
- Soules MR, McLachlan RI, Ek M, Dahl KD, Cohen NL, Bremner WJ. Luteal phase deficiency: characterization of reproductive hormones over the menstrual cycle. The Journal of Clinical Endocrinology and Metabolism. 1989. https://pubmed.ncbi.nlm.nih.gov/2506214/
This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.
