Int J Thyroidol.  2021 May;14(1):46-49. 10.11106/ijt.2021.14.1.46.

Spurious Thyroid Function Test Results due to Biotin Interference: a Report of Three Cases and a Literature Review

  • 1Department of Internal Medicine, Chonnam National University Hwasun Hospital, Chonnam National University Medical School, Gwangju, Korea


Biotin (vitamin B7) is a water-soluble vitamin used as a co-enzyme for carboxylases essential for human metabolism. The high affinity to streptavidin makes biotin an important substance in immunoassays. Excessive biotin intake due to over-the counter supplements has become problematic because of the effects on laboratory test results. There have been no reports of biotin-induced thyroid immunoassay interference in Korea. We report three patients with papillary thyroid cancer who showed false thyrotoxicosis on follow-up laboratory examinations with a literature review. The patients’ medical history should be thoroughly questioned and patients should be informed to curtail consuming biotin before laboratory tests to avoid assay interference. Non-biotinylated assays can be considered if it is impossible to withhold the supplements. These methods will prevent physicians from making incorrect decisions that could result in an inappropriate treatment for their patients.


Biotin; Interference; Immunoassay; Thyroid function tests
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