A-076 Abbott Alinity ci System Automated Sample Interference Indices for Immunoassays

Abstract

Abstract Background The Alinity ci system Sample Interference Indices (HIL) provides a more accurate and consistent method for interpretation of interferents than time consuming visual interpretation. The Alinity c system uses specific wavelength pairs and an algorithm to provide a Sample Interference Index that can correlate with sample interference due to hemolysis, bilirubin and turbidity present in serum/plasma samples. Using just a single aspiration from a sample, the individual or all 3 indices can be selected to be reported. These values in combination with assay specific endogenous interference can be used to determine the potential for HIL interference in the Alinity i immunoassays. Methods The HIL methodology will be reviewed and discussed. The study followed Clinical and Laboratory Standards Institute (CLSI) protocol EP7-A2. Interferences were studied up to concentrations of 1000 mg/dL for hemoglobin, 30 mg/dL for bilirubin (unconjugated) and 1000 mg/dL for triglycerides in serum. Serial dilutions of the sample pools were analyzed in replicates of 4 on the Alinity c system. A cumulative summary was compiled of the Hemolysis, Icterus and Lipemia indices for 100 Alinity immunoassays. Results Using known concentrations of hemoglobin, bilirubin and Intralipid, the Abbott Semi-Quantitative Index (concentration range in mg/dL) and Qualitative Index (Blank, 1+, 2+, 3+ 4+) were confirmed on the Alinity c system. Correlation studies show a linear relationship (r = 1.0) of the indices with increasing concentration of analyte. An easy-to-use guide was created that combines the HIL Qualitative and Quantitative Index scores with the assay specific interference results to provide a guide to potential interferents for the Alinity i immunoassays. This guide provides background information on the causes of HIL interferences, conversion factors from Conventional to SI units and denotes the specific concentrations of interferents which could lead to an over or under estimation in the presence of hemoglobin, bilirubin and/or lipemia. In addition, the effects of the influence of two or more HIL interferents on assay reported results is discussed. The majority (96%) of the 100 immunoassays had no significant interference using samples with elevated H, I or L index values. The remaining 3 assays showed slight interference. Conclusion The Alinity ci system provides a simple and automated procedure for determining the sample indices (HIL) for patient specimens. These HIL values in combination with assay specific endogenous interference results can be used to determine the potential for HIL interference in the Alinity i immunoassays to avoid misdiagnosis.