From the Research
It is recommended to stop taking biotin supplements for at least 7 days before having thyroid function tests, as biotin can interfere with laboratory methods used to measure thyroid hormones, potentially leading to incorrect diagnoses or masking of thyroid conditions. Biotin, also known as vitamin B7, can cause falsely high results for free T4 and T3, and falsely low results for TSH, particularly when using biotin-streptavidin binding technology 1, 2, 3, 4. The degree of interference depends on the biotin dose and specific laboratory methods used for testing. High-dose biotin supplements (commonly found in hair, skin, and nail vitamins at doses of 5,000-10,000 mcg) can cause more significant interference than lower doses found in multivitamins 3.
Some key points to consider:
- Biotin interference can lead to misleading thyroid function test results, potentially causing incorrect diagnoses or treatment plans 1, 2, 3, 4
- The interference can be significant, especially with high-dose biotin supplements 3
- Informing healthcare providers about biotin supplement use is crucial before thyroid testing 1, 2, 3, 4
- Recent studies have highlighted the importance of considering biotin interference in thyroid function tests, particularly in patients taking high-dose biotin supplements or undergoing immunotherapy 5
In clinical practice, it is essential to prioritize the patient's safety and well-being by ensuring accurate thyroid function test results. Therefore, stopping biotin supplements for at least 7 days before testing is a reasonable recommendation to minimize the risk of biotin interference 1.