Sex Hormone Binding Globulin (SHBG)

What is Sex Hormone Binding Globulin?

SHBG is a protein produced by the liver that binds and transports sex hormones (testosterone, estrogen, DHT) in the bloodstream. It regulates hormone availability by controlling how much remains free and biologically active. SHBG levels are influenced by age, hormones, metabolic health, and medications.

Why is it Tested?

Doctors order SHBG to help interpret testosterone and estrogen results, particularly when symptoms don’t match total hormone levels. It’s essential for calculating free androgen index and understanding why someone might have hormone-related symptoms despite normal total hormone levels.

Normal Ranges

Reference ranges vary by lab, age, and sex. General adult guidelines:

Men: 10–57 nmol/L
Women: 18–144 nmol/L

Women typically have higher SHBG levels than men due to estrogen’s stimulating effect on SHBG production.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Low SHBG

Low levels may indicate:

Insulin resistance or diabetes
Obesity or metabolic syndrome
Hypothyroidism
Androgen excess conditions

High SHBG

Elevated SHBG may suggest:

Hyperthyroidism
Liver disease
Estrogen therapy
Aging (in men)

How to Track Over Time

SHBG changes reflect metabolic and hormonal shifts that affect hormone activity. Declining SHBG often signals worsening insulin resistance, while rising levels may indicate improving metabolic health or thyroid function changes. Monitoring SHBG helps optimize hormone therapy and assess overall endocrine health.

Sex Hormone Binding Globulin