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.

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.

Hematology tests of blood anticoagulated with magnesium sulphate.

Venous blood treated with magnesium sulphate (MgSO4) at blood collection was used for hematology tests. Complete blood counts and automated leukocyte differentials were obtained using a hematology analyzer, and the results obtained for blood treated with MgSO4 were similar to those for blood treated with dipotassium ethylenediaminetetraacetic acid (EDTA K2). Coagulation tests such as activated partial thromboplastin time, platelet factor 3 availability and prothrombin time were dose-dependently affected by the use of MgSO4. Thrombin time was prolonged by addition of MgSO4, and fibrin concentrations determined by coagulometry tended to decrease with addition of MgSO4, although fibrin concentrations determined by the weighing method were unaffected by MgSO4. MgSO, was thus found to potently inhibit blood coagulation and can be used as an anticoagulant for hematology tests.

Problems related to rapid methods for erythrocyte sedimentation rate test and their solution.

The erythrocyte sedimentation rate (ESR) test is one of the most common and traditional laboratory tests in the world. It reflects both plasma concentration of acute-phase proteins of large molecular size and anemia (International Council for Standardization in Hematology, 1993). The ESR test method is easy to perform and inexpensive. Therefore, it is used today as a routine test worldwide. However, the ESR has some demerits, in requiring a large volume of sodium citrate or ethylenediamine tetraacetic acid (EDTA) blood and at least 2-hour testing time. When ESR is tested manually, incorrect results are obtained if the ESR test tube is not stood strait-up and vertically (Dobashi et al, 1994). Reading error for the meniscus line and surrounding temperature at the testing site cause inaccuracy (Manley, 1957). The 2-hour testing time is not practical for modernized automated laboratories. Its test procedures present the risk of infection from contact with pathogen-bearing blood (Imafuku and Yoshida, 2001). In this context, several kinds of simple, rapid and safe methods have been developed. Of these new systems, we selected 4 and evaluated their performance. This paper reports critical reviews of such devices.