Is Biotin Baffling Your Lab Results?

Is Biotin Baffling Your Lab Results?
Morgan Stoa, PharmD, Community University Health Care Center

Background: Biotin (Vitamin B7) is an over the counter supplement that is commonly used for stronger hair, skin, and nails. The recommended daily intake for biotin is 30 µg for adults, but over the counter supplements often provide as much as 5,000-10,000 µg per dose. Emerging evidence from the Endocrine Society and other professional organizations suggests that this simple water-soluble vitamin may actually be causing interference in common lab results. Biotin is a major component in a number of immunoassays commonly used on hormone markers such as TSH, T4, T3, prolactin, and parathyroid hormone.

This is particularly troublesome in thyroid tests where biotin can lead to the false diagnosis of Graves’ disease. Large doses of biotin can cause TSH results to be falsely low and T3, T4, and TSH antibody results can be falsely elevated, which mimics the lab results that are diagnostic for Graves’ disease.Recent reports have described several patient’s being erroneously diagnosed with Graves’ disease despite having no clinical symptoms of the disease based solely on their lab results. 

Evidence: A recent study by Lani et al. investigated four different clinical laboratories with different diagnosis systems to see if short-term use of biotin 10 mg (10,000 µg) per day in healthy adults could alter the levels of 11 hormone and non-hormone analytes in six healthy adults. Patients gave blood samples before starting biotin, after a week of taking biotin 10 mg/day, and a week after discontinuation of biotin. Tests included TSH, T4, free-T4, T3, free-T3, parathyroid hormone, prolactin N-terminal pro-brain natriuretic peptide (NT-proBNP) and 25-hydroxyvitamin D (25-OHD). In male patients, they also tested ferritin and prostate specific antigen.

Several of the tests found a statistically significant difference in the laboratory results from baseline and after biotin administration. Biotin ingestion was associated with statistically significant false increases in 4 assays: Roche cobas e602 with total T3, free T3, and free T4; and the Siemens Vista Dimension 1500 free T3. Further, it falsely increased the Roche cobas 25-OHD results by a mean of 9.25 ng/mL [95% CI 5.72-12.8 ng/mL; P<0.001] higher than the baseline.  Biotin also resulted in a statistically significant decrease with the Ortho Clinical Diagnostics Vitros parathyroid hormone concentrations by about 61% from baseline and pro-BNP levels by an average of more than 13.9 pg/mL. When comparing the serum biotin levels from baseline and a week after biotin discontinuation there was no statistical difference between these two time periods. However, it was noted that the mean biotin concentration was increased a week after discontinuation of biotin. The study found no interference in any of the 14 nonbiotinylated assays studied. 

Discussion: This study identified that there are some potentially clinically important assay interferences that can occur with biotinylated assays when patients ingest mega doses of biotin such as 5,000-10,000 µg per dose. While there are a number of articles by different professional groups discussing the risk, this study contributed to better understanding of the problem beyond anecdotal evidence. The study was small and only with a total of six participants. Additionally seven of the biotinylated assays were not affected by seven days of biotin therapy, unlike what would be expected.  Although biotin is a water-soluble vitamin that is easily excreted, patients in this study only took the biotin supplement for a total of seven days. In practice, some patients may take biotin daily for extended periods, so further data on the effects of long-term use would be required. 

Clinical Impact: The Endocrine Society suggests asking patients about any supplements they may be taking, including biotin, when discussing and reviewing laboratory results. They further recommend thorough screening for symptoms of Grave’s Disease and other hormone syndromes to be used in comparison to laboratory results when making a diagnosis for patient. It is also not well established how long a patient should discontinue their biotin supplement before performing the laboratory test. As it is water-soluble, it is thought to wash out of the body quickly. The Endocrine Society was unable to recommend a specific time-frame for discontinuation. However, they acknowledge that even a day off of the supplement can improve the testing results if another diagnostic test cannot be performed.

1.       Barbesino, Giuseppe. “The Unintended Consequences of Biotin Supplementation: Spurious Immunoassay Results Lead to Misdiagnoses. American Association for Clinical Chemistry. December 1 2016. Access November 3 2017.

2.       Seaborg, Eric. “January 2016 – Thyroid Month: Beware of Biotin”. Endocrine News. The Endocrine Society. January 2016. Accessed November 3 2017.

3.       Lani, D et al. Association of Biotin Ingestion with Performance of Hormone and Nonhormone Assay in Healthy Adults. Journal of American Medical Association. 2017; 318(12): 1150-1160. Accessed November 3 2017.