Biotin in high doses can interfere with certain medical tests.

• A. False
• B. True
• C. Not sure
• D. Depends on the test

Answer: (B)

Biotin at high doses can interfere with certain medical tests that rely on biotin-streptavidin binding in their immunoassay design. When someone is taking large amounts of biotin, the excess biotin in the blood can saturate streptavidin or outcompete biotin-labeled reagents, which disrupts the normal binding and signaling the assay relies on. This can lead to results that are falsely high or falsely low, depending on how the test is built. Thyroid function tests (like TSH and free T4) are classic examples where interference has been reported, and other immunoassays for hormones, cardiac markers, and some vitamin or fertility tests can also be affected. The key point is that the risk grows with the dose, and the exact direction of the error depends on the specific test format. If you’re taking high-dose biotin and need blood work, tell the clinician, as they may advise stopping the supplement for a day or two before testing to avoid interference.