Clinical Information

Biotin is a water soluble B complex vitamin (vitamin B7 or vitamin H) that is an essential cofactor for the synthesis of fatty acids, catabolism of branched chained amino acids, and for gluconeogenesis. It is usually found at relatively low endogenous concentrations in patients on a normal diet. However, biotin can be found in over-the-counter multi-vitamins, prenatal vitamins, and dietary supplements marketed for hair, skin, and nail growth. Additionally, treatment of certain progressive multiple sclerosis patients with high doses of biotin has been reported to be beneficial. Biotin supplementation from either over-the-counter or prescription sources can result in extremely elevated circulating biotin. Some immunoassays in the clinical laboratory use chemistry that utilizes the high affinity and avidity that biotin has for binding avidin (or streptavidin). As a result, high serum biotin concentrations can yield inaccurate laboratory results in laboratory assays that utilize this biotin-streptavidin chemistry. Specifically, specimens with high biotin can yield falsely decreased results when the testing methodology utilizes sandwich-based methods or falsely increased results when the methodology utilizes competitive binding methods. Each clinical laboratory method that utilizes biotin-streptavidin chemistry has a defined biotin concentration limit above which serum biotin can interfere with assay results. This test measures free biotin concentrations in serum and can be used to determine whether a patient has high biotin concentrations that are likely from biotin supplementation/treatment.