[Reference values of laboratory tests: a useful and important epidemiologic contribution of the Centers for health tests].

Since 1969 the Centre for Preventive Medicine in Nancy has been carrying out health examinations of the eastern region of France (Lorraine, Champagne-Ardenne). The clinical chemists at the Centre of Preventive Medicine have made a great contribution to the concept and the description of biochemical reference values for which the transferability to other health centres must be verified. Knowledge of reference values and biological variations facilitates the interpretation of weak modifications of biological constituents which are observed in preventive medicine. Reference values can be used to compare two populations (comparing reference values between to two) or to compare an individual observed value to the reference values obtained in the various population groups. In the long term, these reference values could become a useful education tool for patients coming for health examination. It should be possible for each subject to follow, throughout his life, the evolution of his biological constituents and to detect any deviation towards a pathology.