RESUMO
BACKGROUND: Hemolysis may occur in vivo, under pathological conditions, or in vitro, related to pre-analytical errors. Hemolyzed samples may produce unreliable results, leading to errors in diagnostic and monitoring evaluations. This study aims to evaluate the interference of in vitro hemolysis on the interpretation of the parameters of the blood cell-counting performed by the impedance method. METHODS: Peripheral blood samples were collected in anticoagulant K2-EDTA and subsequently divided into three 1.0 mL aliquots. The first aliquot was not subjected to any intervention, and the second and third aliquots were passed 5 and 10 times through a small-gauge needle to produce scalar amounts of hemolysis. Hematological tests were performed by Hemacounter 60-RT 7600® . RESULTS: Comparison of the samples with different degrees of hemolysis showed a decrease in red blood cells count and hematocrit counts and increase in mean corpuscular hemoglobin concentration and platelet count in samples with a high degree of hemolysis. According to the accepted clinical point of view, the samples with a high degree of hemolysis exceeded the desirable bias, presenting decrease in red blood cells count, hematocrit and mean corpuscular volume, and increase in red cell distribution width, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and platelet counts. However, samples with a mild degree of hemolysis showed only a slight increase in mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and platelet count. CONCLUSION: This study demonstrated that in vitro hemolysis can decrease the clinical and analytical reliability of the assessment of the blood count.