Sex Hormone-Binding Globulin (SHBG)
Also known as: SHBG
SHBG is the hepatic protein that binds testosterone and estradiol in circulation. It is the single most important context marker for interpreting total testosterone correctly.
What Sex Hormone-Binding Globulin measures
Sex Hormone Binding Globulin (SHBG) is a liver-produced glycoprotein that binds testosterone, estradiol, and DHT with high affinity. Bound hormones are biologically inactive; SHBG levels therefore set the size of the free, bioactive hormone fraction.
Clinical significance
SHBG is the most underappreciated marker in androgen interpretation. Elevated SHBG masks androgen insufficiency by suppressing free testosterone despite a normal total; low SHBG can produce symptoms of androgen excess at unremarkable total values. SHBG also correlates with metabolic health — low SHBG associates with insulin resistance, NAFLD, and metabolic syndrome.
How oMeds reviews it
Inside Hormone Optimization, SHBG is always co-drawn with total + free testosterone and estradiol. Patterns drive the decision tree: high SHBG → favor preparations and dosing strategies that protect free fraction; low SHBG → metabolic workup co-equal with hormone review.
Standard clinical reference intervals
Lab-reported reference ranges from established standards bodies. These are diagnostic thresholds — they do not represent optimization targets.
Source: LabCorp adult male reference interval
Source: LabCorp adult female reference interval
oMeds optimization targets
Editorial bands that inform provider-reviewed conversations. These are wellness targets, not diagnostic thresholds.
An SHBG band of 20-45 nmol/L preserves free testosterone bioavailability while reflecting metabolic resilience in provider-reviewed optimization.
oMeds optimization ranges are editorial targets that inform conversations with a licensed provider. They are NOT diagnostic thresholds and do not replace lab reference ranges.
Sex Hormone-Binding Globulin — frequently asked
What raises SHBG?
Aging, hyperthyroidism, oral estrogens, anticonvulsants, liver disease, and prolonged caloric restriction. Provider review contextualizes SHBG against lifestyle, medication history, and adjacent thyroid + liver markers.
What lowers SHBG?
Insulin resistance, NAFLD, exogenous androgens, obesity, hypothyroidism, and certain glucocorticoids. Low SHBG often co-presents with cardiometabolic risk and is rarely an isolated finding.
Source literature
How this entity relates
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Conditions this biomarker informs
Co-reviewed biomarkers
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