Verifying the nonreporting hemolysis index for potassium, phosphate, magnesium, AST, LDH, iron, CA 19-9, and vitamin D, using Beckman Coulter AU5800 and DxI800 automated analyzers.

Abstract

Hemolysis is a common reason for nonreporting results in biochemistry and is measured using the hemolysis index (HI), with nonreporting limits set for analytes by manufacturers. To verify the nonreporting HI limit for potassium, phosphate, magnesium, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), iron, CA19-9, and vitamin D on the Beckman Coulter AU5800/DxI800 analyzers. Hemolysate was created from EDTA-lined tubes of whole blood using an osmotic shock procedure. The hemolysate underwent serial dilutions with saline and was spiked in paired serum. The delta changes in HI and analyte concentration were measured, assessed using regression analysis, and compared against calculated reference change values. A linear relationship between increasing HI and increasing analyte concentration (R2> 0.9) was observed for potassium (y=0.8864x), phosphate (y=0.1079x), magnesium (y=0.0678x), AST (y=29.035x), and LDH (y=350x). Increasing HI values did not have a linear effect on iron (y=-0.2544x), CA19-9 (y=2.7019x), or vitamin D (y=8.036x) concentrations. The results from this experiment support increasing the HI nonreporting limit to 100mg/dL for potassium; 200mg/dL for magnesium; and 300mg/dL for phosphate, CA19-9, and vitamin D. The iron assay is not affected by hemolysis as high as 500mg/dL. The current HI nonreporting limit of 50mg/dL is appropriate for LDH.