SHBG vs Free Androgen Index
SHBG is the carrier protein that binds testosterone. FAI is the ratio of total testosterone to SHBG, expressed as a percentage. Together they explain why two patients with identical total testosterone can have very different bioactive testosterone.
SHBG is decisive context for interpreting any testosterone reading — it is always read with total T.
FAI is decisive when total testosterone is borderline or when SHBG is out of range.
Educational. Final pathway selection is provider-reviewed via synchronous video consultation against your biomarkers, history, and goals.
Frequently asked
Is FAI the same as free T?
Similar in spirit — FAI is a calculated index; calculated free T uses SHBG and albumin and is preferred when albumin is available.
What lowers SHBG?
Insulin resistance, hypothyroidism, obesity, and exogenous androgens — all interpreted in provider review.
Take the optimization assessment.
The adaptive assessment maps your symptoms, history, and goals to candidate pathways — and routes you into provider review.
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