Objectives. Complete blood count (CBC) is one of the most commonly requested laboratory tests in clinical practice. The interpretation of laboratory results is a comparative decision-making process, and reference intervals have an important role in laboratory reports. In Estonia, each laboratory uses its “own” reference values for CBC. A difference between reference ranges causes confusion in the interpretation of results. The aim of the study was to develop common reference values for CBC in adults.
Methods. The collaborating four laboratories recruited first time blood donors and appropriate healthy volunteers by invitation, drew blood, and measured CBC-diff parameters. The participants had to feel subjectively well, did not have a history of chronic disease or use of prescription medications. They were assessed by using completed questionnaires and defined exclusion criteria. The EDTA blood samples were tested within 3 hours after collection. The CBC-diff parameters were measured by the Sysmex analysers XE-2100, XE-5000, XN-2000, XN-1000 (Kobe, Japan). Each participating laboratory has been accredited according to ISO 15189:2012. A nonparametric method was used to calculate the reference ranges.
Results. Blood samples from a total of 314 clinically asymptomatic and apparently healthy subjects were evaluated and a final of 259 subjects were included in the study: 132 men and 127 women. The reference intervals were calculated for the following parameters: RBC, Hb, Hct, MCV, MCH, MCHC, RDW, Plt, MPV, Pct, P-LCR, PDW, IPF, WBC, IG#, Neut#, Lymph#, Mono#, Baso#, Eo#.
Conclusions. Population based CBC reference ranges were established. The results provide the basis for harmonization of automated CBC–diff reference intervals across laboratories. This would assist laboratory specialists and clinicians in gaining a uniform interpretation of test results for clinical management of patients.