Hemolysis effect on coagulation test results.

Background: Due to the high risk of developing thrombosis, the majority of diabetic patients are receiving antithrombotic therapy. During routine laboratory monitoring of these agents a certain number of hemolyzed coagulation samples are usually observed. As hemolysis influence on coagulation test results hasn't been extensively studied, our aim was to investigate the effect of hemolysis on routine coagulation tests: prothrombin time (PT), activated partial thromboplastin time (aPTT) and fibrinogen by using serum hemolysis indices (HI) and measuring free plasma hemoglobin concentrations as indicators of the degree of hemolysis. Materials and methods: We measured PT, aPTT and fibrinogen in 30 hemolyzed and nonhemolyzed plasma samples from the same patients on the coagulation analyzer BCSR XP (Siemens Healthcare Diagnostics) on two wavelengths (405 and 570 nm). Free plasma hemoglobin concentrations were determined spectrophotometrically and measurement of HI was performed on biochemistry analyzer Cobas c6000 (Roche). In-vitro hemolysis influence on coagulation test results was studied by adding hemolysate in normal and pathological plasma pool samples (final hemoglobin concentrations: 0-10 g/L). Correlation between free plasma hemoglobin concentrations and coagulation test results in hemolyzed samples was assesed. Results: Hemolysis affects all routine coagulation tests independently of HI or free plasma hemoglobin concentrations. The major hemolysis influence was observed for aPTT in a normal plasma pool sample, whereas only minor influence was observed for PT in a pathological plasma pool sample. Linear correlation between free plasma hemoglobin concentrations and HI was confirmed. Conclusions: Although hemolysis affects all three determined coagulation parameters, the influence on each parameter is different, not always correlating with the intensity of hemolysis. Our results indicate that HI is a reliable indicator of the degree of hemolysis. Routine measurement of HI could provide a better estimation of hemolysis influence on coagulation test results and reduce the number of unnecessary and repeated blood testing. [ABSTRACT FROM AUTHOR]