Evaluation of hematological values obtained with reference automated hematology analyzers of six manufacturers.

We evaluated assays of the same fresh blood samples with six different types of reference automated hematology analyzers developed by the following manufacturers: Beckman Coulter, Sysmex, Bayer, Abbott, Nihon Kohden and Horiba. Fresh whole blood samples treated with dipotassium ethylenediaminetetraacetic acid (EDTA K2) were collected from three healthy adult volunteers. The complete blood counts (CBC) including red blood cell count (RBC), hemoglobin (Hgb), hematocrit (Hct), mean corpuscular volume (MCV), white blood cell count (WBC), platelet count (Plt), reticulocyte percentage (Ret) and leukocyte differential counts including % neutrophils (Neu), % lymphocytes (Lym) and % monocytes (Mon) were surveyed with a reference automated hematology analyzer from each manufacturer. The process from sampling to analysis was performed according to procedures in hospital clinical laboratories. RBC, Hgb, Hct and MCV exhibited allowable differences within 5% of mean value among all instruments. Large differences greater than 10% of mean value in WBC, Neu and Lym between Horiba and other manufacturers, and in Plt between Nihon Kohden and other manufacturers, were observed. Ret and Mon exhibited large differences over 10% of mean value among almost all of the instruments tested. This survey suggests that all parameters exhibiting differences greater than 10% of mean value among instruments should be improved for clinical use to ensure good external quality control in blood cell counting and leukocyte differential counting using automated instruments.

Problems on national and locale external quality assurance schema (NEQAS and LEQAS); based on Japanese experience.

The quality and stability of surveillance materials is a critical issue to perform good external quality assessment schema. In the case of nationwide surveillance, more stable materials are required than those in the case of locale external quality control schema. For locale surveillance, fresh blood, plasma or serum materials are prepared for hematology and chemistry tests. On the other hand, dried materials are used for the chemistry test and semi-fixed blood is used for hematology tests in the national surveillance. However to evaluate automated white cell differential in hematology, there has been no good materials. We therefore prepared a mixture of EDTA and ACD solution for our locale surveillance. It gave us excellent results on the differential when we used it within 3 days after blood collection.