Biotin Interference with Thyroid Function Tests

Clinical Implications and Management

• The British Journal of Pharmacology reports that there is no evidence of a direct interaction between biotin and levothyroxine absorption or metabolism 1
• According to Clinical Gastroenterology and Hepatology, biotin does not bind to levothyroxine and reduce its absorption, unlike bile acid sequestrants such as cholestyramine or colestipol 2
• The Annals of Internal Medicine recommends that multiple TSH tests should be performed over a 3-6 month interval to confirm abnormal findings, especially when biotin use may be present 4

Safety of Biotin

• Clinical Nutrition states that biotin toxicity is unlikely even at high doses, with no upper limit established 5
• Clinical Nutrition also reports that no adverse effects have been shown for both oral and IV administration of pharmacological doses of biotin up to 5 mg/day for prolonged periods 6