Biotin

Biotin (vitamin B7) is a water-soluble B vitamin essential for energy metabolism, hair, skin, and nail health. A biotin test measures circulating biotin levels, which can be low due to insufficient dietary intake, malabsorption, or certain medications. Biotin deficiency is rare but can cause hair loss, skin rashes, and neurological symptoms. Biotin supplementation has become popular for hair and nail health, though evidence is mixed. This test helps identify true deficiency versus assessing supplement adequacy.