Abstract
Objectives: A working group (WG) for the standardization of blood cell morphology was established between the Japanese Association of Medical Technologists (JAMT) and the Japanese Society for Laboratory Hematology (JSLH). The WG established reference intervals (RIs) of observed WBC differential on the basis of the new classification criterion for the neutrophil system proposed by the Committee for the Standardization of Blood Cell Morphology of JSLH, and diffuse RIs were introduced nationwide in Japan. Methods: Exclusion criteria for reference individuals were based on the “Collaborative derivation of reference intervals of major clinical laboratory tests for nationwide use in Japan” of the Japanese Committee for Clinical Laboratory Standards (JCCLS). Reference individuals were selected from among healthy volunteers engaged in medical-care-related works or physical examination. Age and sex distributions were adjusted to obtain a final sample size of 936 individuals aged 18 to 67 years. Two hundred cells were counted under 400× magnification by an accredited hematologist or a directed laboratory technologist using the new classification criterion for the neutrophil system. Result: The distribution of the complete blood count (CBC) of the reference individuals was parallel to the RIs of JCCLS, and the validity of the reference individuals was confirmed. There were no significant differences in sex and age after observing leukocytes of peripheral blood. There were no significant RI differences between the parametric method and the nonparametric one, and the latter method was established as common RIs. Conclusion: The common RIs determined by observing leukocytes of peripheral blood are to be used nationwide. It was suggested that the networks of the JAMT should be utilized so that the RIs established in the present study become widely available.
