Biotin is used as a dietary supplement by many people, especially those trying to improve the look of their hair, skin and/or nails. However, recent research has shown that biotin can interfere with laboratory testing for thyroid function, which could lead to misdiagnosis and unnecessary treatments.

Biotin and It’s Uses

Biotin (Vitamin B-7) is a common B-vitamin that is needed for the metabolism of proteins, fats and carbohydrates. Symptoms of deficiency include thinning or loss of hair, loss of hair color, red rash around the eyes, nose and mouth, depression, listlessness, hallucinations and tingling in the arms and legs. People use biotin to improve hair, skin and nail growth; there is also evidence that biotin may help improve blood sugar control in diabetics when used in combination with chromium.

Biotin and Thyroid Labs

However, biotin can also interfere with labs used to diagnose and treat disorders of the thyroid. In particular, biotin supplementation can cause an artificial increase in Free T4 and Total T3 levels without affecting TSH levels. This can lead to the erroneous diagnosis of hyperthyroidism or Graves disease. Unfortunately, there is typically no mention of this interaction in laboratory reports and most endocrinologists/doctors are not aware of this issue.

How Biotin Interferes with Thyroid Labs

Biotin is used in almost all immunoassays because these tests rely on a complex that involves biotin (biotin–streptavidin) to either bind the assay’s antibodies to a capture surface or capture them once they have reacted with a patient sample. This can interfere with the most commonly used thyrotropin and thyroid hormone assays. The results are falsely increased or decreased according to whether a competitive method of measurement (for free T4 and total T3) or noncompetitive method (for thyrotropin) are used. In addition, biotin can also interfere with the method used for detection of anti–thyrotropin receptor antibodies. Together, these effects can result in a laboratory pattern indistinguishable from that of Graves’ disease.

What To Do If You Take Biotin and Have Thyroid Issues

If you are taking biotin and your thyroid labs just don’t make sense and/or if your labs indicate that you have abruptly developed Graves disease, talk to your doctor. Discontinue your biotin and retest in a week; it might just save you from unnecessary anti-thyroid treatments.


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