Abnormal circulating inhibin level Elevated circulating inhibin A concentration 2024-03-09T17:10:09Z The concentration of inibin A in the blood circulation is above the upper limit of normal. Inhibin A and inhibin B are related dimeric protein hormones and endocrine regulators of the reproductive axis. Specifically, inhibin inhibits FSH secretion from the anterior pituitary. The inhibins are synthesized by the gonads and are themselves modulated by FSH.