SHBG
Sex hormone-binding globulin (SHBG) is a glycoprotein produced by the liver that binds and transports sex hormones (testosterone, estradiol, DHT) in the blood. SHBG-bound hormones are biologically inactive — only free and albumin-bound fractions are bioavailable. SHBG effectively controls how much active sex hormone is available to tissues.
Why it matters: SHBG is essential for correctly interpreting testosterone and estradiol levels. High SHBG reduces bioavailable hormones even when total levels appear normal. Low SHBG increases bioavailable hormones even when total levels appear low. SHBG is also an independent marker of metabolic health — low SHBG strongly predicts insulin resistance and type 2 diabetes.
May increase with:
May decrease with:
What is SHBG?
Sex hormone-binding globulin (SHBG) is a glycoprotein produced by the liver that binds and transports sex hormones (testosterone, estradiol, DHT) in the blood. SHBG-bound hormones are biologically inactive — only free and albumin-bound fractions are bioavailable. SHBG effectively controls how much active sex hormone is available to tissues.
What might a high or low SHBG mean?
SHBG is essential for correctly interpreting testosterone and estradiol levels. High SHBG reduces bioavailable hormones even when total levels appear normal. Low SHBG increases bioavailable hormones even when total levels appear low. SHBG is also an independent marker of metabolic health — low SHBG strongly predicts insulin resistance and type 2 diabetes.
What is the typical reference range for SHBG?
The general-population reference range shown here is 18.3 – 54.1 nmol/L. Reference ranges describe the general population and are not a personal target — discuss your results with your physician.
What can affect SHBG?
It may be higher with: Aging, Liver disease (cirrhosis), Hyperthyroidism, Oral estrogen (birth control, HRT), Anorexia nervosa, Anticonvulsants (phenytoin, carbamazepine), HIV medications. It may be lower with: Obesity and insulin resistance, Hypothyroidism, Nephrotic syndrome, Androgenic medications, Corticosteroids, Type 2 diabetes, PCOS, Growth hormone excess.