Insignificant interference of Elevit in pregnant women serum samples with HBsAg immunoassay on Sysmex

Background The pregnant women often take Elevit as the multivitamin supplement which has a substantial amount of biotin that might potentially interfere with the HBsAg immunoassay performed by the prevalent Sysmex system in clinical laboratories. We therefore wanted to determine this, so that the therapeutic intervention on the hepatitis B virus infection during pregnancy and birth would not be missed. Methods Elevit was both serially diluted in vitro and orally taken by healthy volunteers whose blood samples were then taken at different time points. All samples were added to a serum sample with a known result of HBsAg and then measured by Sysmex. The Abbott immunoassay system was used as the control as it involves no streptavidin‐biotin binding in the reagent set. Besides, the HBsAg results were compared between the pregnant women taking or not taking Elevit. Results Biotin at 25 ng/mL in the Elevit started to suppress the HBsAg and reached about 50% suppression at 100 ng/mL on Sysmex. In the volunteers, biotin reached the peak concentration at 2 hours. However, their blood samples showed no suppression on the HBsAg detection by Sysmex. In samples from pregnant women who took Elevit, the HBsAg results by Sysmex were highly correlated with those by Abbott ( R 2  = 0.96). Comparison of the results from Sysmex between the age‐ and pregnancy‐matched females with and without Elevit intake showed no difference. Conclusion Elevit intake in pregnant women shows no significant interference with HBsAg immunoassay on Sysmex.