Complete blood count: absolute or relative values?

Abstract

Background: For many years, relative values based on 100 quantified cells have been used to assess blood counts in the field of hematology. However, modern blood counting machines have recently made it possible to determine absolute counts. Thus, the current study assessed whether the determination of relative values, based on 100 cells counted, or the determination of absolute values is more accurate in hematology.Methods: To calculate the errors of absolute counts and of quotients, we used two independent methods to determine the errors. For the error calculation, we first performed a Gaussian error calculation. Second we identified the errors using daily control checks and examined the high limit of the actual errors (precision) on the Sysmex XE5000 hematological analyzer.Results: Our findings indicated that the accuracy of the relative values was always much higher compared to the absolute values.Conclusion: This finding can be explained by combined errors which affect absolute cell counts and which are directed for all cell counts of one run into the same direction. These types of errors are reduced by quotient formation as shown here for the basophils. The accuracy of the absolute values obtained from the hematology machines of the latest generation was acceptable due to the very high number of cells quantified.