SHBG
The protein that binds testosterone and estrogen — controls how much is biologically active.
What is it
SHBG is a protein produced by the liver that binds sex hormones (primarily testosterone and estradiol) in circulation. When SHBG is high, less hormone is biologically free; when SHBG is low, more hormone is free.
Why it's measured
SHBG is essential context for interpreting testosterone and estradiol values. Insulin resistance, thyroid status, and liver function all influence SHBG levels in research literature.
Reference range
Standard laboratory reference
Men: 10 – 57 / Women: 18 – 144 nmol/L
Reference ranges vary by laboratory. Your individual reference range will appear on your test report and should be interpreted by your physician in the context of your overall health profile.
What results may indicate
Elevated
Often seen with hyperthyroidism, certain medications, or aging in research literature. Reduces free hormone levels.
Lower
Has been associated with insulin resistance, metabolic syndrome, and obesity in published research.
These associations are general. They are not a personal diagnosis or prediction. Discuss your individual results with your physician in the context of your full health profile.
When it's measured
Measured alongside total testosterone for free testosterone calculation and metabolic context.
Related markers
Measured in
A complete look at your heart, hormones, metabolism, inflammation, and longevity systems — drawn at Quest or LabCorp, reviewed by a U.S.-licensed physician.
Explore the Apex Panel →This information is for general educational purposes only and is not medical advice. Lab results alone are not intended to diagnose, treat, or cure any condition and do not replace the advice of a healthcare provider. OPTML does not offer medical advice, a diagnosis, medical treatment, or any form of medical opinion.