Abnormal circulating inhibin B concentration Increased circulating inhibin B concentration 2024-03-09T17:10:09Z The concentration of inhibin B in the blood circulation is above the upper limit of normal. Inhibin B high in blood 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.