[Present status and problems of the normal values (clinical reference range) of the laboratory tests--results of a questionnaire survey in university hospitals in Japan].
The normal values (clinical references range) of the laboratory tests differs among hospitals due to the differences in: (1) the kinds of instruments and reagents used, (2) how the population for study was selected and the size of the population was, (3) when the specimens were taken, (4) how they were stored until use, and (5) how the data obtained were calculated and (6) who evaluated the results. In this study, questionnaires regarding the above-mentioned points were sent to the heads of the clinical laboratories in 80 university hospitals in Japan. Answers were received from 71 laboratories (the rate of recovery was 88.8%). The normal range of potassium, uric acid, total cholesterol, enzyme activities [ALP, LDH, CHE, AST (GOT) and ALT (GPT)] in the university hospitals in Japan varied. It is not ideal to use different reference values in different hospitals. However, it is impossible to prepare a standard manual to obtain the normal range at present. When the inter-hospital differences become small enough to obtain one normal range for the Japanese peoples, a standard manual for normal values should be made.