Inhibin B reaches a peak in the early- to mid-follicular phase, and a second peak at ovulation.
Inhibin A reaches its peak in the mid-luteal phase.
Inhibin is produced in the gonads, pituitary gland, placenta and other organs.
In men, it is a hormone that inhibits FSH production.
It is secreted from the Sertoli cells, located in the seminiferous tubule inside the testes.
Activin is a related peptide that counteracts inhibin.
Quantification of inhibin A is part of the prenatal quad screen that can be administered during pregnancy at a gestational age of 16-18 weeks. An elevated inhibin A (along with an increased beta-hCG, decreased AFP, and a decreased estriol) is suggestive of the presence of a fetus with Down's syndrome. As a screening test, abnormal quad screen test results need to be followed up with more definitive tests.
It also has been used as a marker for ovarian cancer.
^ van Zonneveld P, Scheffer G, Broekmans F, Blankenstein M, de Jong F, Looman C, Habbema J, te Velde E (2003). "Do cycle disturbances explain the age-related decline of female fertility? Cycle characteristics of women aged over 40 years compared with a reference population of young women". Hum Reprod18 (3): 495-501. PMID 12615813.
^ Skinner M, McLachlan R, Bremner W (1989). "Stimulation of Sertoli cell inhibin secretion by the testicular paracrine factor PModS". Mol Cell Endocrinol66 (2): 239-49. PMID 2515083.
Aitken D, Wallace E, Crossley J, Swanston I, van Pareren Y, van Maarle M, Groome N, Macri J, Connor J (1996). "Dimeric inhibin A as a marker for Down's syndrome in early pregnancy". N Engl J Med334 (19): 1231-6. PMID 8606718.
^ Robertson D, Pruysers E, Jobling T. "Inhibin as a diagnostic marker for ovarian cancer". Cancer Lett. PMID 17320281.
^ Robertson D, Pruysers E, Burger H, Jobling T, McNeilage J, Healy D (2004). "Inhibins and ovarian cancer". Mol Cell Endocrinol225 (1-2): 65-71. PMID 15451569.