Serum testosterone and its binding globulin during senescence

Abstract

Purpose: The aim of this work is to analyze age-related changes in providing tissues with steroid hormones (androgens [A], mainly testosterone [T]) by means of specific steroid transport protein of the blood (testosterone-binding globulin, [TeBG]) and to propose new informative approach for reliable early diagnostics of impending hypogonadism in elderly men. Methods: Methods are analytical. Results and conclusions: Authors develop new approach for assessment of age-related physiological changes in supply of steroids (in particular T) by specific transporting them testosterone-binding globulin (TeBG). This work substantiates the following statements: a) existing common beliefs about circulating A (including ‘exchangeable’ and ‘free’ testosterone levels – [Texch], [Tfree]) do not match their true state of affairs concerning presence, interaction, interchange and transmission of А into target cells; b) blood pool of ‘ТeBG-Т-ТeBG’-complex should correctly be called the ‘functional Т-dimer’ (FTD); c) venous blood FTD-content ‘mirrors’ the ‘potentially active’ (bioavailable) testosterone molecules conc. ([Tact]) in arterial blood (i. e. which capable to be transferred into target cells from capillaries, [Tact] = [FTD] ); d) age-dependent rise in circulation of ‘nonfunctional’ TeBG-molecules (ТеBGnf) caused by accumulation with age the ‘senescence factor’ which inhibits needed FTD-formation; e) [FTD]- measurements can be useful for early diagnosis of impending hypogonadism in elderly men