Sex Steroids Binding Globulin: the evolution of views about biological functions and diagnostic significance in normal and pathological conditions

Abstract

Sex steroid hormones (androgens, estrogens) play a critical role in the endocrine regulation of human body functions in normal and in various pathologies. Numerous complex mechanisms of their transportation from the site of synthesis to target cells are involved in the process of realization of their functions by sex steroid hormones, among which the most important role is played by sex steroids binding globulin (SSBG), synthesized in the liver and entering the systemic circulation. Until recently, SSBG was considered practically only as a specific transport system of sex steroids (androgens, estrogens) to target cells. Early studies have demonstrated an increase in the SSBG level in the blood as a person’s age increases, however, only relatively recently a polymorphism of the SSBG gene was established, which determines the genetically determined different degree of affinity of this transport protein to sex steroid hormones (androgens, estrogens) in different people, which allows us to consider SSBG not only as a unique individual transport protein of blood, but also as a unique serum regulator of the activity and tissue bioavailability of sex steroids. Modern studies have also shown close interrelations of the serum level of GSPS with some human diseases, which allows us to consider this transport protein not only as their potential serological marker, but as a direct independent mechanism of their pathogenesis.