Sex Hormone-Binding Globulin (SHBG, Sex steroid-binding protein, Testis-specific androgen-binding protein, Testosterone-estradiol-binding globulin, Testosterone-estrogen-binding globulin)

Sex-hormone-binding globulin (SHBG) is a β-globulin that specifically binds steroid hormones. Its molecular weight is 86 kDa/mol. The major site of SHBG synthesis is thought to be the hepatocytes. Its production is regulated by androgen/estrogen balance, thyroid hormones, insulin and dietary factors, among others. SHBG is involved in the transport of sex steroids in plasma. Its concentration is a major factor regulating their distribution between protein-bound and free states. Determination of SHBG concentration is mainly of importance in the evaluation of mild disorders of androgen metabolism and it allows identification of women with hirsutism who are likely to respond to estrogen therapy. Testosterone/SHBG-ratios correlate well with both measured and calculated values for free testosterone, and help to discriminate between subjects with excessive androgen activity and normal individuals.