Sex Hormone Binding Globulin (SHBG) is a sex hormone-binding glycoprotein produced in the liver that regulates the bioavailability and biological activity of sex hormones, mainly testosterone and estradiol. SHBG levels are measured on automated immunoassays, indicated to assess reproductive health in conditions related to polycystic ovary syndrome, hypogonadism, and endocrine disorders affecting androgen or estrogen metabolism.