Investigation of sex-hormone binding globulin interference in direct radioimmunoassays for testosterone and estradiol.
The aim of this study was to find reasons for the interference of sex-hormone binding globulin (SHBG) in direct radioimmunoassays (RIAs) for testosterone and estradiol. 125I-labeled testosterone and estradiol were compared with 3H-labeled testosterone and estradiol for their affinity to SHBG. The 3H-labeled steroids bound far more avidly to SHBG than did the corresponding 125I-labeled steroids. The SHBG concentration in the standard matrix of two kits was significant. Finally, 3H-labeled steroids were compared with 125I-labeled steroids for their affinity to the antibody supplied with the kits. The 125I-labeled steroids bound more avidly than did the 3H-labeled steroids to the corresponding antibodies. Direct testosterone and estradiol results would be influenced according to the SHBG in the sample, as observed.
Masters
A M
AM
Endocrine Research Laboratories, King Edward Memorial Hospital for Women, Australia.
Hähnel
R
R
D003429:Cross Reactions; D004958:Estradiol / Q000097:blood*; D006801:Humans; D011863:Radioimmunoassay; D011933:Reagent Kits, Diagnostic; D012738:Sex Hormone-Binding Globulin / Q000032:analysis*; D013739:Testosterone / Q000097:blood*
D011933:Reagent Kits, Diagnostic; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol