What does the Biotin (Vitamin B7) test measure?

Why is Biotin (Vitamin B7) measured?

Clinical biotin deficiency is rare in individuals consuming a varied diet, because the vitamin is widely distributed in foods and produced by gut flora. When deficiency does occur — through prolonged raw-egg-white consumption (which contains the binding protein avidin), biotinidase deficiency, parenteral nutrition without biotin supplementation, or certain anticonvulsants — it manifests as alopecia, scaly dermatitis, conjunctivitis, ataxia, and developmental regression in infants. Conversely, high-dose biotin supplementation (often marketed for hair and nail health or used at pharmacological doses in multiple sclerosis) can interfere with a wide range of immunoassays, producing spurious laboratory results.

Reference ranges

Standard reference

Approximately 200–1200 ng/L; assay- and supplementation-dependent.

Functional medicine optimal

Consensus optimal thresholds are not established; adequacy is generally inferred from the absence of clinical deficiency and normal carboxylase activity.

Units

ng/L, nmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.