The Effect of Hemolysis on Biochemical Tests: Determining Interference Cutoffs and Managing Hemolytic Samples

Hemolysis is a common source of interference in biochemical tests, potentially leading to significant errors in clinical decision-making and patient management. This study aimed to evaluate the impact of varying degrees of hemolysis on routine biochemical analytes and to find a local hemolytic index (HIX) cutoff for safe reporting.

This experimental study was conducted on 30 serum samples from healthy individuals with normal biochemical profiles. Baseline concentrations of 20 routine analytes were measured using a DIRUI CS-1200 analyzer. To simulate hemolysis, increasing concentrations of autologous hemolysate were added to each sample, creating three grades of hemolysis based on HIX (mild, moderate, and severe). All analytes were remeasured, and the absolute and relative biases were calculated against baseline levels. These biases were then compared with the CLIA-defined total allowable error (TEa) to obtain the safe reporting cutoff for each analyte.

All analytes showed a positive bias with increasing hemolysis, though the magnitude of interference varied significantly. LDH, uric acid, AST, and total bilirubin, in that order, were more impacted by hemolysis. In mild hemolysis (HIX < 0.5), none of the analyte biases exceeded TEa limits (p value < 0.05). In moderate and severe hemolysis, however, most exceeded acceptable limits. Based on these results, a HIX cutoff of 0.5 was regarded for reporting mildly hemolyzed samples.

Hemolysis interference is both analyte- and system-dependent. Laboratories are recommended to conduct similar research tailored to their local laboratory settings and population to improve analytical quality and reduce unnecessary specimen rejection.