Capacity of the Testosterone-Binding Globulin in Human Plasma and Influence of Specific Binding of Testosterone on Its Metabolic Clearance Rate

Abstract

The binding capacity (TeBC) and binding index (BI) of the testosterone-binding globulin (TeBG) have been studied in several groups of patients. Before puberty, TeBC and BI are similar in both sexes and in the adult female range, but are higher in adult females than in adult males. Increased. TeBC and BI values were observed in male hypogonadism in hyperthyroidism, and in males with chronic asthmatic bronchitis or cirrhosis of the liver. During pregnancy increased TeBC and BI values were observed but at delivery low normal TeBC and BI values were found. Decreased TeBC and BI values were observed in hirsutism, in female obese patients, and in patients with the nephrotic syndrome. Progestogens do not increase TeBC, whereas estrogens (contraceptives) increase significantly the TeBC and BI values; decreased values were observed after testosterone treatment of females; corticoids decrease the TeBC values of patients with chronic asthmatic bronchitis. The metabolic clearance rate (MCR) of testosterone, determined in basal conditions and after infusion of testosterone, increased with the non-TeBG bound fraction but at identical non-TeBG bound fraction, the MCR was higher in males than in females; when, however, the testosterone level had been chronically increased in females by im injection of testosterone-enanthate, the MCR was similar to the MCR in males.