Inhibin B Levels in Hypothyroid Males

Abstract

Background: The primary role of inhibin B is the regulation of gametogenesis via negative feedback on the production of follicle stimulating hormone (FSH) by the pituitary. Methods: We studied 14 males with primary hypothyroidism due to various etiologies to determine if they exhibited hypogonadotrophic hypogonadism involving the reproductive segment of the gonadotrophic axis. Levels of inhibin B, FSH, luteinizing hormone, testosterone, free thyroxine, and thyrotropin were measured. Results: The mean level of inhibin B in males with primary hypothyroidism was found to be approximately half that of normal males. The FSH level remained within the normal range and no reciprocal increase was observed as occurs in other conditions with reduced inhibin B. Conclusions: Our results indicate that primary hypothyroidism has a significant effect on inhibin B levels without reciprocal increase in FSH, which is consistent with a hypogonadotrophic hypogonadal state affecting the reproductive segment of the gonadotrophic axis.

Effect of thyroxine replacement on leydig cell and sertoli cell function in men with hypothyroidism

“…However, semen analysis was not done in this study. [ 28 ] In our subjects, INHB values at baseline were comparable to that of the normal controls of two studies done in the Indian population by Geetika et al , and Abidet al[ 29 30 ] While we did not observe a significant change in INHB values before and after treatment, levels of serum INSL3, a hormone secreted by the Leydig cells, increased significantly after the achievement of euthyroidism. The source of INHB was believed to be exclusively from Sertoli cells, till recently.…”

Pituitary-testicular axis dysfunction in methimazole-induced hypothyroidism in rats

“…It being the case that our results for gonadotropin and testosterone concentrations are also similar to those obtained by Donnelly et al . (8), we observed hypogonadotropic hypogonadism in males with methamizole-induced hypothyroidism, hence the decreased concentration of gonadotropins despite the zero increase in and concentration insufficient for inhibition of inhibin B. What mars the credibility of such an evident statement and requires further explanation is the increased concentration of inhibin A, which may be responsible for the dysfunctioning pituitary-testicular axis.…”

“…Similar results of inhibin B concentrations to ours in male rats with hypothyroidism were obtained by Donnelly et al . (8) in hypothyroid men. We obtained an inhibin B ratio hypothyroid to normal males (0.59) similar to the ratio found by these authors (0.55).…”

“…This is due in part to a decrease in thyroid hormone levels, as they play a key role in regulating maturation and growth of testicles as well as in controlling functions of Sertoli and Leydig cells both in adolescent and adult life, and restoring euthyroid state usually normalises impaired functions of the reproductive system (19, 27, 28). Naturally occurring hypothyroidism causes severe pituitary-testicular axis dysfunctions and hypogonadotropic hypogonadism in men, lowering gonadotropins, testosterone, and inhibin B concentrations (8).…”

Elastographic and morphological testicular changes in hypothyroidism – an experimental study

“…Iatrogenic hypothyroidism, as a major clinical problem especially in people, cats, and other animal species which are treated with methimazole or other antithyroid drugs, influences numerous functions (3, 4, 10, 11, 12, 16). Naturally occurring hypothyroidism, as a systemic disease, leads to pituitary and testicular damage, especially during hypogonadotropic hypogonadism; however, other reasons for these conditions, such as testicular functional changes, have been found (7, 8, 16, 24). Therefore, it probably differs from iatrogenic thyroid gland insufficiency, in that the spectrum of adverse effects of an antithyroid drug depends on the kind of medicine, its dose, exposure time, and the stage of life when treatment was conducted (3, 26).…”