Biotin AGAIN:

It is hard to imagine that years later the exact variable that was intentionally utilized to improve the robustness of an immunoassay is the same factor that now leads to interference and laboratory errors.  Biotin is commonly found in a variety of over-the-counter available supplements, including; daily multivitamins, prenatal multivitamins, biotin supplements, and dietary supplements for hair, skin, and nail growth.  The past 5 years have seen a growing trend in patients using mega-doses of biotin, either through single-sources such as Biotin Supplements or through multiple sources such as multi vitamins combined with other supplements, with the goal of improving appearance and beauty. 1

 Due to the strong binding affinity to streptavidin, biotinylated antibodies and analogues are utilized in many common immunoassays. 2, 3   Biotin supplementation, in the common dosage of 10 mg per day, can interfere with immunoassays leading to incorrect laboratory results and the potential for clinical misinterpretation.   A potential misdiagnosis resulting from biotin interference could occur when, for the same patient, a laboratory receives a falsely low TSH result in combination with a falsely high FT4 result.  With this clinical picture and constellation of lab results the physician could conclude that the patient is presenting with Graves’ disease, when in fact they have normal thyroid function or possibly even hypothyroidism. 4

The simple explanation is that biotin supplements mimic the presence of the analyte being tested.  Therefore, in a sandwich assay the biotin replaces the locations where the analyte binds, and the analyte concentration is effectively decreased resulting in a “false low” result.  Conversely in a competitive assay, excess biotin binds to the streptavidin sites which block the binding of the analogue –biotin-signal antibody resulting in a “false high” for the analyte of interest.

Diagnostic information is critical to the medical care of your patients.  The entire line of Tosoh immunoassays are “biotin free”, and this feature equals no risk of biotin interference, providing peace of mind while avoiding having to burden your patients with returning for their blood draw after refraining from taking all of their vitamins and supplements. .And what of testing situations when returning for a blood draw later is not possible, such as with Troponin?

By using immunoassay tests with no possibility of biotin interference,  your patients will not be inconvenienced nor will there be risk that test results could possibly lead to costly and inaccurate medical outcomes as a result of biotin.   

In November of 2017, the FDA sent out a warning to the public regarding biotin and the potential for both “False Low” and “False High” test results.5  What prompted this alarm was a laboratory test returning with a falsely low Troponin result, unfortunately leading to incorrect diagnoses and to a patient’s death. In the warning, the FDA reminds clinicians and laboratory personnel to be on the lookout for biotin interference and to ask patients if they are taking biotin supplements prior to drawing their blood.

Despite the fact that biotin interference has been a factor in lab testing since 1999, and numerous articles have been published, the FDA’s warning caused recognition and awareness of the biotin problem to heighten overnight.  This led to a request by the IFCC (International Federation of Clinical Chemistry) that all Troponin manufacturers list by test, biotin interference and at what threshold interference occurs.  These interference values can be found at and are current as of April of 2018.

Tosoh immunoassays do not rely on biotin or biotinylated reactions in their test designs, and have always been “biotin free”.  Tosoh Bioscience, Inc. will be exhibiting at 2018’s AACC – stop by booth #1938 to visit the “Biotin Free Zone” and experience the peace of mind offered by biotin-free test designs.  Leave at least one worry behind. 


  1. Sloan, A. E. & Hutt C.A. (2015, September 8). “Repositioning Nutraceutical Products for Growth markets.Retrieved January 17, 2017, from Nutraceuticals World: ”http// growth-markets
  2. Li, et al “Association of Biotin Ingestion with Performance of Hormone and Nonhormone Assays in Healthy Adults”, JAMA 2017:Vol 318, Number 12
  3. Piketty, M-L et al “False biochemical diagnosis of hyperthyroidism a streptavidin-biotin based immunoassays: the problem of biotin intake and related interferences. Clinical Chemistry and Laboratory Medicine, Published Online (2016)
  4. Elston, MS et al. (2016). Factitious Graves’ Disease Due to Biotin Immunoassay Interference- A Case and Review of the Literature. J. Clin Endocrinol Metab. 3251-3255