RESUMEN
Hemolysis frequently causes preanalytical errors in laboratory measurements. We aimed to develop a quality improvement indicator for evaluating the extent of inappropriate procedures causing hemolysis in clinical samples collected in medical care units. We defined the threshold value of the hemolysis index (H index) causing significant interference with analyte measurement and analyzed the H index values of clinical samples in relation to the threshold. The H index threshold value causing a 10% bias in the measurement of lactate dehydrogenase was found to be 25. The monthly mean H index and monthly frequency of samples with an H index >25 were significantly different among the types of ward (P=0.001, respectively), and significantly decreased after replacement of a laboratory centrifuge lacking temperature control (20.6±0.58 vs 23.30±1.08, P=0.01; 23.4±1.69% vs 32.6±1.78%, P=0.01). The monthly mean H index and the monthly frequency of samples with an H index above a threshold value may be useful quality improvement indicators for detection of inappropriate procedures in the acquisition and handling of blood samples in medical care units.