Background: Biotin is commonly used in many commercial assays. It is known that exogenous biotin can interfere with these tests, however not all manufacturers have issued warnings or reassurances. Interference can lead to increased or decreased concentrations of an analyte depending on the assay format. We assessed the effect of biotin interference on all relevant assays performed in our laboratory. We investigated a variety of concentrations ranging from the recommended daily intake up to very high dose supplementation to determine the level at which a particular assay may be affected. Methods: Samples were spiked to give estimated serum concentrations equivalent to doses of 0.05 – 3600 mg/day exogenous biotin. Each spiked sample was tested and the result compared to a baseline. Biotin interference was deemed to have taken place if the spiked value exceeded the allowable uncertainty of measurement. Results: Not all assays utilising biotin were affected. We confirmed interference claims made by Manufacturers. However, a few of these assays showed that biotin levels below those stated in safety notices could cause some degree of interference. Three assays for which there had not been a warning were shown to be affected. Conclusions: In house checks should be performed on all assays containing biotin as a reagent. This allows the laboratory to understand performance characteristics and dosage effects for causing potential interference. Our data provides a guide for the level of biotin which may cause false positive or false negative results.
Swallow et al. (Tue,) studied this question.