[Characterization and problems regarding clinical reference ranges of aged subjects on clinical chemistry]

Various characteristic clinical laboratory testing data related to clinical chemistry were collected from 11 institutes across the nation, and age-related clinical reference values, reference intervals and within-subject biological variations were calculated. Using these calculated results, characterization of aged-related reference ranges and the method of determining an aged subject's testing values were investigated. From these results, the following facts became clear. Estimation of health-associated reference intervals for aged subjects was very difficult. As the aged subject's reference values differ remarkably by sex and age on several test items, sex- and age-related clinical reference values are necessary. In case of the mass screening survey which utilizes preceding healthy values, we should decide by within-subject biological variation. We usually use reference ranges to decide whether the measured values are located within these ranges, and must use a differential value to speculate regarding a particular disease. These results indicate that multiple standard must be prepared for each clinical laboratory testing value, and that it is ideal to be able to select a suitable standard for the subjects state. To select a suitable standard clinically, we need an expert system. For this purpose, much more basic data concerning reference ranges, differential values and so on must be accumulated.