SHBG

Sex Hormone Binding Globulin (SHBG) is a protein produced mainly by the liver that binds tightly to sex hormones, primarily testosterone and estradiol, regulating their availability to tissues. High SHBG reduces free hormone levels, while low SHBG increases them. SHBG levels are influenced by factors like age, obesity, insulin resistance (lowers SHBG), thyroid function (hyper raises, hypo lowers), liver function, and estrogen levels (raises SHBG). It is essential for accurately interpreting Total Testosterone levels and calculating Free/Bioavailable Testosterone.