Also known as vitamin B7, coenzyme R, W Factor, and vitamin H

Tests for Biotin Levels

The best tests for biotin levels are done on urine samples.

Three different tests are considered most accurate in detecting biotin levels:5

  • β-hydroxyisovalerate is an amino acid produced as the amino acid leucine (from dietary protein) is metabolized in the body. To complete the metabolism of leucine, biotin is needed at this part of the process. Increased amounts of β-hydroxyisovalerate in the urine are an early indicator of insufficient biotin levels - including deficiencies caused by antibiotic use.4
  • Decreased biotin levels in the urine; detectable within 10 days of biotin-decreasing event (e.g., consumption of avidin).4-5
  • Dysfunctional metabolic activity of propionyl-CoA carboxylase, one of the enzymes biotin binds to.5

Levels of biotin in plasma are not considered a good indicator of biotin status. Even in the presence of clinical symptoms of biotin deficiency, plasma levels may appear normal.4

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