Pre-analytical variation of some haematological quantities

Background: It is customary to assume that pre-analytical variation is negligible if all pre-analytical sources of variation have been standardised. The aim of this study was to quantify the pre-analytical variation of some haematological quantities frequently measured in clinical laboratories. Methods: The experimental design considers different sources of pre-analytical variation that usually occur day-to-day for samples from patients. Results: The results demonstrate that for concentrations of erythrocytes, haemoglobin, leukocytes, neutrophilocytes (segmented) and lymphocytes, and for the volume fraction of erythrocytes ("packed cell volume'') in blood, the pre-analytical variance is not negligible. Conclusions: We suggest that these variances should be taken into account when estimating the uncertainty of measurement for patient results.