Influence of hemolysis on clinical chemistry parameters determined with Beckman Coulter tests - detection of clinically significant interference.

The aim of this study was to examine the influence of hemolysis on 25 clinical chemistry parameters and to compare the resulting bias with clinically significant differences and the manufacturer's specifications. Using freeze-thawing of the treated blood aliquot of each subject (N = 17), four hemolysis levels were prepared with hemolysis index (HI) and hemoglobin concentration as follows: (+)=0.5-0.99 g/L, (2+)=1-1.99 g/L, (3+)=2-2.99 g/L and (4+)=3-4.99 g/L. All analytes were tested on the Beckman Coulter AU480 analyzer using proprietary reagents. It was considered that the interference was detected if the 95% confidence interval for mean differences (%) between hemolyzed and non-hemolyzed samples did not include zero. Clinically significant interference was judged against reference change value (RCV). Hemolysis interference was detected for: alpha-amylase, alkaline phosphatase (ALP), aspartate aminotransferase (AST), total and conjugated bilirubin, creatine kinase (CK), CK-MB, ɣ-glutamyltransferase (GGT), iron, lactate dehydrogenase (LD), magnesium, potassium, total protein and uric acid at HI=(1+); alanine aminotransferase (ALT) and phosphate at HI=(2+); urea at HI=(3+); albumin and cholinesterase at HI=(4+). Even at the greatest hemolysis degree, HI=(4+), no interference was detected for calcium, chloride, creatinine, C-reactive protein (CRP), glucose and sodium. Clinically significant difference was exceeded for LD at HI=(1+); CK-MB at HI=(2+); AST and potassium at HI=(3+); total bilirubin at HI=(4+). The presented results did not support the manufacturer's claim for CK and GGT. Establishing HI thresholds for reporting or suppressing test results is the responsibility of each laboratory, taking into account the manufacturer's data, but also its own investigations.