Dynamics of the binding capacity of plasma sex hormone binding globulin (SHBG) for testosterone and dihydrotestosterone during puberty.

Plasma sex hormone binding globulin binding capacity (SHBG-b.c.) has been evaluated in 203 normal subjects (114 males and 89 females) aged 3 to 51 years. The subjects were divided into groups: prepubertal, early pubertal (Tanner's Stages 1 and 2), late pubertal (Tanner's Stages 4 and 5) and adult. In both sexes, plasma mean values of SHBG binding capacity both for dihydrotestosterone (DHT) and testosterone (T) were significantly higher in prepubertal subjects, falling during puberty to adult levels. During pubertal development DHT-BG binding capacity and T-BG binding capacity showed different plasma values with respect to sex and phase of puberty. Our data do not support an absolute relationship between sex hormones and SHBG binding capacity, but suggest other mechanisms as well: (a) SHBG modifies its physicochemical properties during puberty, or (b) the binding capacity is the result of a pool of proteins which modifies its composition during pubertal evolution.