Identification and measurement of sex hormone binding globulin (SHBG) and corticosteroid binding globulin (CBG) in human saliva

Abstract

Sex hormone binding globulin (SHBG) and corticosteroid binding globulin (CBG) were detected by specific immunoassays in mixed-saliva taken from normal men and women. The immunochemical identity of both proteins was demonstrated by parallelism between dose response curves generated by serial dilutions of saliva and standards in the immunoassays. In addition, the specific removal of both proteins by incubation with steroid affinity-chromatography gels demonstrated the integrity of their steroid binding activity. The mean +/- SD concentrations of SHBG (pmol/l) and CBG (microgram/l) in mixed-saliva taken from normal volunteers were as follows: men (n = 6) 19 +/- 10 and 38 +/- 18; women (n = 6) 63 +/- 60 and 72 +/- 71 and women during late pregnancy (n = 6) 282 +/- 168 and 92 +/- 80, respectively. The data indicate that the concentrations of SHBG and CBG in saliva represent approximately 0.1% of plasma concentrations. It is suggested that these proteins pass from the blood to saliva in a non-specific manner, and may influence the steroid content of saliva under certain physiological circumstances.