Unraveling the Need for standardization of Homocysteine Assay: Insights from the Results of External Quality Assurance.

Homocysteine is an intermediate product of the biosynthesis of methionine and cysteine and a sulfhydryl-containing amino acid. The study aims to assess the difference between the estimated levels of homocysteine by different automated systems on Biorad External Quality Assurance Services samples and the imprecision of examination of homocysteine levels below the limit of detection in External Quality Assurance Services samples by proficiency testing providers. This study involves the analysis of Biorad External Quality Assurance Services sample reports of two cycles (cycles 10 and 11) for homocysteine level evaluation performance. Our study demonstrates the wide difference in the bias percentage of homocysteine levels when bias was calculated with the peer mean and the method mean. There was a substantial increase in bias percentage for the Siemens Advia Centaur XP machine for samples with levels of homocysteine below the limit of detection. Our study also demonstrated that Siemens Advia and Siemens Atellica were evidently underestimating homocysteine levels when compared with other platforms. The use of Standard Reference Material for traceability of calibrators will ensure the standardization of assays between different manufacturers. The variation observed in the External Quality Assurance Services results of homocysteine highlights the impending requirement of standardization of assays using Standard Reference Materials.