How Biotin Induces Misleading Results in Thyroid Bioassays: Case Series

In 2019, two studies demonstrated that biotin supplementation can interfere with thyroid bioassays, leading to false results and potential misdiagnosis. The first study involved three patients taking high-dose biotin supplements, which caused misleading thyroid function test results. The second study presented four cases where individuals ingesting 20-30 mg of biotin showed a false increase in thyroid function tests, leading to a false diagnosis of Grave's disease. In all cases, the results returned to normal after biotin withdrawal. These studies concluded that clinicians should be aware of the potential for biotin interference in thyroid function tests, especially in patients taking biotin supplements. Biotin should be discontinued for at least 48-72 hours before thyroid assaying by any commonly used biotin-streptavidin immunoassay.