From the FDA Drug Label
Biotin levels higher than the recommended daily allowance may cause interference with some laboratory tests, including ... hormone tests, and may lead to incorrect test results. The biotin may affect Thyroid-Stimulating Hormone (TSH) testing, as it can interfere with hormone tests and lead to incorrect test results 1.
- Biotin supplementation should be considered when interpreting TSH test results.
- It is essential to inform the healthcare provider about biotin supplementation to ensure accurate laboratory test results.
From the Research
Biotin supplements should be stopped at least 2-3 days before thyroid function tests to avoid interference with TSH levels, as high-dose biotin can falsely lower TSH levels and falsely elevate T3 and T4 levels in laboratory tests, as reported in a recent study 2. This interference occurs because many modern immunoassays use biotin-streptavidin binding technology, and excess biotin in a patient's blood can disrupt these testing mechanisms, as explained in a study published in the Journal of medical case reports 2. The interference is most significant with biotin doses of 5 mg or higher, though even lower doses (1-2 mg) may affect results in some assay systems, as noted in a study published in Cureus 3. Some key points to consider:
- Patients taking biotin supplements for hair, skin, and nail health (typically 5-10 mg daily) or high-dose biotin for multiple sclerosis (300 mg daily) are most at risk for this interference, as reported in a study published in Nutrition (Burbank, Los Angeles County, Calif.) 4.
- Inaccurate thyroid test results can lead to misdiagnosis or inappropriate treatment changes, as highlighted in a case report published in the Journal of oncology pharmacy practice 5.
- Healthcare providers should routinely ask patients about biotin supplementation before ordering thyroid tests, and laboratories should consider noting this potential interference on test reports, as recommended in a study published in Nederlands tijdschrift voor geneeskunde 6.
- If biotin cannot be discontinued, alternative testing methods not affected by biotin interference may be used, as suggested in a study published in the Journal of medical case reports 2.
- This interference is temporary and resolves once biotin is cleared from the system, as reported in a study published in Cureus 3.