Biotin Supplements: A Hair‐Raising Challenge to the Analytical Accuracy of Clinical Immunoassays

Abstract

Streptavidin(avidin)/ biotin and anti‐biotin/biotin reactions have played a significant role in the development of the field of clinical immunoassay(IA) and are now used in many of the FDA‐cleared IA's that are used for patient care. A marked increase in the use of high‐dose biotin supplements by the general public has led to a steady increase in the incidence of false positive and false negative IA results among subjects that consume biotin at doses of > 1 mg/day. The goals of this study were to investigate the risk of significant biotin interference in IA's that utilize biotinylated reagents and biotin binding proteins and to compare their manufacturer‐established interference thresholds (IFTs) with the serum biotin concentrations that have been observed in single‐dose pharmacokinetic studies of oral biotin therapy in humans.In June of 2016, we reviewed current versions of the manufacturer's “Instructions For Use” (IFUs) for each of the IA methods on 8 of the most widely used automated clinical IA systems. A method was considered to be potentially vulnerable to biotin interference when it utilized a streptavidin/biotin or an anti‐biotin/biotin reaction. Vulnerable methods were further characterized as to the manufacturer‐determined threshold for significant interference by exogenous biotin in a patient sample and whether or not the IFU identified biotin interference as an analytical limitation of the method.We found that 0 to 100 % of the IA's performed on a particular assay system were potentially vulnerable to biotin interference. Depending on the platform, the methods that were at risk for biotin interference were designed to measure a wide variety of analytes including thyroid, steroid and polypeptide hormones, serum proteins, infectious disease serologies, cardiac markers, tumor markers, biomarkers of anemia and autoimmune diseases, and immunosuppressive drugs. The IFTs reported by the manufacturers varied considerably from method to method within a particular assay system and from system to system. For some methods, there was no evidence that an IFT study had been performed (Table 1, n/a). Additional analyses showed that methods with IFTs of <200 nmol/L were likely to be at risk for generating inaccurate test results for samples from subjects whose daily oral biotin intakes are > 1 mg per day. This risk increases as the IFT of the method decreases, increases with the size of a subject's biotin dose, and decreases when specimen collection is delayed 24 to 48 hours after the subject's last oral dose. Until a permanent solution to the problem of biotin interference is offered up by the clinical diagnostics industry or mandated by the FDA, healthcare workers should be aware that biotin supplements can cause falsely increased or decreased results for a wide variety of routine IA's that are used in patient care and should contact the clinical laboratory that performs their testing for up to date information on which of their methods are vulnerable to interference and how to prepare the subject and time the blood draw in order to the minimize the risk of an inaccurate result. Biotin Interference in Immunoassays Performed by Eight Automated Clinical Assay Systems Multi‐Test Assay System Total IA's # Vulnerable to Biotin Interference Biotin Interference Thresholds range (nmol/L) Roche Elecsys® 81 81 21 – 491 Ortho Vitros® 43 29 10 – 82 Siemens Dimens on® 26 21 205 – 2000 (3 r/a) Siemens Centaur® 67 18 10 – 1000 (6 n/a) Beckman Coulter Access®/DXI® 48 14 10 – 1000 (9 n/a) Abbott Architect i2000® 42 2 120 (1 n/a) Siemens Immulite 2000® 64 D ‐‐‐‐‐‐ Diasorin Liaison XL® 42 D ‐‐‐‐‐‐