Interpretation of the results of laboratory tests depends on the clinical problem they are used for – diagnosis, monitoring or screening. For diagnosis of a disease, the patient’s test result is compared to the reference values. However, the most common use of laboratory tests is monitoring of the disease course. In this case the patient’s earlier result serves a natural control point and reference change values should be used. The aim of the study was to find out populationbased reference values and reference change values for full blood count in healthy adults. We also investigated the correlation of different cell-counters and the stability of the blood count parameters in vacuum tube samples. The reference group consisted of 171 females and 94 males from Tartu, Tartu county and Järvamaa, aged 17–79 years. We used three different cell-counters in our study. Repeated measurements from blood samples drawn to EDTA vacuum tubes showed stable and satisfactory results with all analysers during 24 hours. Comparison of different analysers revealed that none of the cellcounters was the best for all parameters. During the 2- year study period the correlations of some parameters changed between analysers.
In this study we found some differences between haematological reference values and literature values. Reference change values express the extent of change in the results of consecutive tests, to be assessed as significantly different. This is the first population-based study of haematological reference values in Estonia.