[Requirements for analytical quality: use of the concept of biological variation]

By using a clinical biochemistry laboratory as an example, the authors show how the analytical quality system practically operates. The advantages of using a three-level model for analytical quality requirements on the basis of biological variations in analytes are discussed. Only does the use of a few normative documents present a possibility of creating an adequate quality system in a specific laboratory. The long-term coefficient of analytical variation is the most important characteristic of analytical quality and a necessary component of the day-to-day work of the laboratory. The level of quality is shown for 27 analytes. Despite the fact that the laboratory uses the same analytical systems as in the world, the level of analytical quality has turned out to be lower than in the best laboratories of Europe.