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Glossary term
SHBG
Also known as Sex hormone-binding globulin - Testosterone-binding globulin
The protein that binds your sex hormones. High SHBG hides low free testosterone behind a normal total.
Sex hormone binding globulin (SHBG) is a liver-made protein that binds ~98% of circulating testosterone and a big share of estradiol. Only the unbound fraction is biologically active. Male reference ranges run ~18-54 nmol/L; above 50 nmol/L often leaves free testosterone functionally low even when total reads mid-normal. Insulin resistance pushes SHBG down; hyperthyroidism, aging, and oral estrogen push it up. Any testosterone panel without SHBG is giving you a third of the picture. See the testosterone-panel guide for how to read it.
- Symbol
- SHBG
- Unit
- nmol/L
- Typical range
- Adult men ~18-54 nmol/L.
Medically reviewed byDr. Lena Okafor, MD
Medical Director - updated April 2026How we review
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