Hormones
Sex hormone binding globulin (SHBG)
Included in Baseline and Complete.
Compare membershipsThis carrier protein shapes how much hormone is available.
SHBG is a protein, made mostly in the liver, that binds testosterone and estrogen in your blood. Hormone attached to SHBG is held in reserve, so your level helps explain how much of your sex hormones your tissues can use.
SHBG puts your testosterone result in context.
Two people with the same total testosterone can have very different amounts of free, usable hormone if their SHBG differs. That's why SHBG is often measured with total testosterone and used to calculate free testosterone or the Free Androgen Index.
Lower SHBG is associated with insulin resistance, type 2 diabetes, excess body weight, an underactive thyroid, and, in women, PCOS. Higher SHBG is associated with aging, an overactive thyroid, liver disease, and estrogen-containing medicines such as birth control pills.
SHBG helps set how much of your hormone is free to act.
Questions
Is a high or low SHBG good or bad?
SHBG isn't good or bad on its own. Its meaning depends on your hormone levels, metabolic health, thyroid function, and medications. A low SHBG alongside other signs of insulin resistance may be worth discussing with a clinician.
Does SHBG matter for women?
Yes. In women, SHBG helps interpret testosterone results, and a low SHBG can mean more testosterone is free to act. Estrogen-containing birth control and hormone therapy raise SHBG, so mention them when your results are reviewed.