lab metric
SHBG (male-only)
Table of contents
Description
Sex Hormone–Binding Globulin (SHBG) is a protein made primarily in the liver that binds sex hormones—especially testosterone—and controls how much is “free” and available to tissues. In men, SHBG is one of the most important reasons total testosterone and symptoms can disagree: if SHBG is high, free/bioavailable testosterone can be low even when total looks normal.
Why it matters
SHBG helps interpret androgen status, especially when evaluating low libido, fatigue, mood changes, or body-composition shifts. It’s typically interpreted with total testosterone, and often free or bioavailable testosterone, plus LH/FSH and clinical context.
What higher or lower SHBG can suggest (general education)
Higher SHBG: can lower free testosterone; seen with aging, hyperthyroidism, some liver conditions, and some medications.
Lower SHBG: can raise free testosterone fraction; commonly seen with insulin resistance, obesity, hypothyroidism, and androgen exposure.
Practical notes
Because SHBG is influenced by thyroid function and metabolic status, it’s often helpful to look at SHBG alongside TSH, A1c/glucose, triglycerides, and liver enzymes.
Educational only, not medical advice. If hormone symptoms are present, labs should be timed appropriately and reviewed with a clinician.
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