Is my SHBG (Sex Hormone-Binding Globulin) normal?
Free blood test checker · Standard + longevity-optimal ranges
What is a normal SHBG level?
SHBG is a liver-produced glycoprotein that traps free hormones (testosterone, estradiol), making them bio-unavailable. Normal range is 20-60 nmol/L. High SHBG effectively reduces free testosterone despite normal total levels — a common cause of "normal labs but symptomatic" low T in men. Insulin resistance artificially suppresses SHBG: low SHBG increases free testosterone but also flags metabolic syndrome. Optimal SHBG balances hormone availability — both extremes cause clinical problems.
| Range | Values |
|---|---|
| Standard Reference | 20–60 nmol/L |
What causes abnormal SHBG levels?
High SHBG: aging, hyperthyroidism, liver disease (cirrhosis), oral estrogen therapy, anorexia, excessive endurance exercise, and anticonvulsant medications. Low SHBG: insulin resistance, obesity, metabolic syndrome, hypothyroidism, type 2 diabetes, PCOS, exogenous androgens, and corticosteroid use. SHBG production is regulated by the balance of insulin (suppresses) and estrogen/thyroid hormones (stimulate).
When should you see a doctor?
See your doctor if SHBG is below 20 nmol/L (evaluate for insulin resistance and metabolic syndrome) or above 60 nmol/L with symptoms of low free testosterone (fatigue, low libido, muscle loss). Always test alongside total testosterone, free testosterone, and metabolic markers (fasting insulin, HbA1c).
SHBG and longevity
SHBG is a key modulator of bioavailable hormones. Conditions that lower SHBG include insulin resistance, obesity, hypothyroidism, and anabolic steroid use. Conditions that raise SHBG include hyperthyroidism, aging, liver disease, and oral estrogen use. Understanding SHBG is essential for interpreting total testosterone — a man with high SHBG and 'normal' total testosterone may actually have clinically low free testosterone. Low SHBG is one of the earliest detectable signs of insulin resistance — often abnormal years before fasting glucose or HbA1c rise. The liver produces SHBG, and hepatic insulin exposure directly suppresses its production: hyperinsulinemia from insulin resistance drives SHBG down, increasing free androgen exposure. In women, this manifests as PCOS-pattern symptoms. In men, the paradox is that low SHBG increases free testosterone but the underlying insulin resistance simultaneously impairs testicular function. Prospective studies show that low SHBG independently predicts development of type 2 diabetes, making it a valuable early metabolic warning signal.
Where to get a SHBG test
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Related biomarkers
These biomarkers are often tested alongside SHBG for a more complete picture.
Frequently asked questions
What is a normal SHBG level?
Why is SHBG important for testosterone interpretation?
What causes high SHBG?
What causes low SHBG?
How does SHBG affect testosterone levels?
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Sources: Reference ranges based on AHA/ACC, ADA, and AACE clinical guidelines. Biological variation data from Ricos/Westgard database. Longevity-optimal ranges reflect targets used by preventive and functional medicine practitioners.
Last reviewed: April 2026. This tool provides general health information and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider about your specific results.