Optimal - The Blog

March 21, 2024

ODX FYI: High-dose Biotin Interferes with Lab Tests

Biotin, also known as vitamin B7 or vitamin “H,” is an essential micronutrient involved in several metabolic reactions, including amino acid catabolism, fatty acid synthesis, and gluconeogenesis, the formation of “new” glucose. Biotin deficiency is relatively rare as adults require only ~30 ug of biotin per day, a level usually met by adequate consumption of fruits, vegetables, whole grains, salmon, chicken, nuts, and dairy products. Absorption of biotin produced by GI bacteria can also be a significant source for humans.

Deficiency is relatively rare, though it can be induced by genetic factors, consuming raw egg whites, restricting intake, or loss of bacterial production. However, biotin supplementation in the milligram range has become popular for skin, hair, and nail support.

Lab Interference of High-Dose Biotin

Unfortunately, such high-dose supplementation can be detrimental, as elevated blood levels interfere with laboratory tests using biotin-based immunoassays. This interference can cause diagnostic errors, especially with thyroid-stimulating hormone (TSH), free T3, and free T4 testing.

Elevated biotin in the blood can falsely decrease analyte concentrations in tests performed with sandwich immunoassay, such as TSH, and falsely increase analyte concentration in tests performed with competitive immunoassay, such as T3, free T3, t4, and free T4. Biotin can also falsely decrease biomarker levels with cardiac troponin and parathyroid hormone testing. The lower doses of biotin found in most multivitamin minerals supplements are less likely to interfere with lab testing (Dasgupta 2022).

Research suggests that supplementation with up to 1 mg of biotin per day does not interfere with laboratory testing, while supplementation with 5 mg or more per day can. Excess intake can be detrimental, and one study found that ~7% of emergency room admissions had elevated serum biotin above 10 ng/mL (10,000 pg/mL). Individuals should wait at least 8 hours after consuming 5-10 mg of biotin before undergoing laboratory testing and at least 72 hours if consuming 100 mg daily or more. Other tests confounded by elevated serum biotin include thyroglobulin, thyroglobulin antibodies, cancer antigens, including CA 19-9 and PSA, cortisol, estradiol, progesterone, testosterone, FSH, LH, SHBG, insulin, C-peptide, ferritin, folate, vitamin B12, vitamin D, DHEA-S, BNP, and NT-proBNP (Li 2020).


  • Quest Diagnostics’ serum biotin range for adults is 0.221 – 3.004 ng/mL (221.0-3004.0 pg/mL)
  • The biotin requirement for most adults is ~ 30 ug/day (NIH ODS).
  • Clinical trials have used up to 300 mg of biotin daily to reduce morbidity associated with multiple sclerosis (Li 2020).

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Dasgupta, Amitava. “Immunoassay design and biotin interference.” Advances in clinical chemistry vol. 109 (2022): 165-183. doi:10.1016/bs.acc.2022.03.005  

Li, Danni et al. “AACC Guidance Document on Biotin Interference in Laboratory Tests.” The journal of applied laboratory medicine vol. 5,3 (2020): 575-587. doi:10.1093/jalm/jfz010

NIH ODS Biotin. https://ods.od.nih.gov/factsheets/Biotin-Consumer/

Quest Diagnostics Biotin https://testdirectory.questdiagnostics.com/test/test-detail/391/biotin-vitamin-b7?cc=MASTER


Tag(s): Biomarkers

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