What is it about?

Biotin (vitamin B7) is a supplement currently available over-the-counter at higher-than-recommended daily doses. Biotin interferes with several important tests including thyroid function tests, testosterone as well as other hormones. This is the case of a patient who presented to our endocrinology clinic with multiple abnormal hormone levels which resulted in additional unnecessary testing, referrals, and even the scheduling of a surgical procedure to remove a suspected testosterone-producing tumor. Finally, the laboratory abnormalities were attributed to biotin interference. This case highlights a ubiquitous problem facing physicians as well as clinical laboratory specialists and chemists in the interpretation of lab results in this setting.

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Why is it important?

The use of supplements is increasing and biotin is found in quantities that exceed RDI in such supplements. Knowledge of biotin's importance for immunoassays and of its potential interference will improve interpretation of abnormal test results. Additionally, due to the widespread use of biotin supplements, the development of non-susceptible laboratory assays is needed.


Primary care providers, endocrinologists, gynecologists and others perform lab testing with assays that are susceptible to biotin interference. Interpretation of falsely-abnormal test results is challenging and requires a high index of suspicion. With this publication, our team aims to raise awareness for this problem and endeavor to find ways to decrease its impact.

Dr Maya Styner
University of North Carolina at Chapel Hill, Department of Medicine, Division of Endocrinology

Read the Original

This page is a summary of: Suspected Testosterone-Producing Tumor in a Patient Taking Biotin Supplements, Journal of the Endocrine Society, May 2018, Endocrine Society, DOI: 10.1210/js.2018-00069.
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