NEW INITIATIVES IN THE STANDARDIZATION OF PROTEIN MEASUREMENTS

Unlike assays for ions and small molecules plasma protein measurements depend entirely on comparison of a test sample with a calibrant, know n as a reference material or standard. Owing to the innate molecular h eterogeneity of plasma proteins it is often impossible to ensure that the calibrator is identical in its behaviour in measurement systems to the test sample. Despite. these fundamental limitations it is clear t hat internationally agreed calibrants are the only way to improve cons istancy of reporting of protein values in biological fluids between me thods and laboratories. Unfortunately, only international units are no t subject to contention and the use of mass values which are not inter nationally agreed, and are re-ascribed during the life of a standard, has jeopardised the value of international calibrants. If mass values are used it must be accepted that they are, to some extent, arbitrary.