High serum levels of biotin can make the assays inaccurate, with lower-than-actual TSH and higher-than-actual thyroid hormone levels. Multiple case reports have documented this happening clinically.1-3 I personally saw a case of this recently in my practice. Katzman and colleagues looked at the prevalence of biotin use in outpatients.4 They found that 7.7% were taking supplemental biotin, while 7.4% had levels of biotin in serum samples that were at a level that could interfere with biotin-based serum assays.
Theoretically, biotin can affect multiple other assays that use the streptavidin-biotin assay. The most concerning of these potential problems is with troponin assays. Biotin can falsely lower troponin assays and this can lead to missing the diagnosis of cardiac injury. The Food and Drug Administration released a warning about this and other biotin lab interactions in November 2017.5 Several studies have demonstrated that this effect can occur at serum levels achievable with available over-the-counter doses of biotin.6,7
Not all troponin assays are affected by high serum levels of biotin: The Gen 5 cTnT assay is the only troponin assay affected.7 I could not find any case reports that have been published where biotin had caused a clinical missed diagnosis with troponins.
Pearls
Consider biotin supplement use when you have patients whose labs look like hyperthyroidism, but clinically do not appear to be hyperthyroid.
Dr. Paauw is professor of medicine in the division of general internal medicine at the University of Washington, Seattle, and serves as third-year medical student clerkship director at the University of Washington. Contact Dr. Paauw at imnews@mdedge.com.
References
1. Charles S, Agrawal N, and Blum M. Erroneous thyroid diagnosis due to over-the-counter biotin. Nutrition 2019;57:257-8.
2. Elston MS et al. Factitious Graves’ disease due to a biotin immunoassay interference – a case and review of the literature. J Clin Endocrinol Metab 2016;101:3251-5.
3. Barbesino G. Misdiagnosis of Graves ’disease with apparent severe hyperthyroidism in a patient taking biotin megadoses. Thyroid 2016;26(6):860-3.
4. Katzman et al. Prevalence of biotin supplement usage in outpatients and plasma biotin concentrations in patients presenting to the emergency department. Clin Biochem. 2018 Sep;60:11-16.
5. “The FDA Warns that Biotin May Interfere with Lab Tests: FDA Safety Communication,” Nov. 28, 2017.
6. Trambas et al. Characterization of the scope and magnitude of biotin interference in susceptible Roche Elecsys competitive and sandwich immunoassays. Ann Clin Biochem. 2018 Mar;55(2):205-15.
7. Frame IJ et al. Susceptibility of cardiac troponin assays to biotin interference. Am J Clin Pathol. 2019 Apr 2;151(5):486-93.