The Practical Application of Reference Method Technology

Abstract

The main value of reference technology will be in the selection of techniques for service use and in defining reference ranges for the concentration of substances in the body fluids of normal individuals. Initially it should find application in the present national and international quality control schemes to distinguish those techniques which, as currently operated, are sound, from those in which accuracy can be demonstrated to be faulty. Over the long-term it is to be expected that when new techniques for service use are submitted for publication, they should not be accepted unless the results which they have produced have been satisfactorily compared with results obtained by the appropriate reference technique. In the application of the reference technique for calcium to the Wellcome Group Quality Control Program it has been shown that two widely used routine methods for calcium in serum tend to give lower results than the reference value at high calcium concentrations, and higher results at low concentrations. Attention can now be focused on this effect with a view to its elimination either by suggesting the modification or abandonment of the techniques in question. Herein lies the key to further improvement in interlaboratory quality control which has recently tended to plateau. Reference technology is likely to be required for four main purposes: 1. The assay of commercial quality control material. 2. The assay, either in prospect or retrospect of material used in national quality control programs. 3. One off measurements required by individual laboratories for development work on instruments and methods. 4. For monitoring the effects of drugs or their metabolites, etc. Definitive methods will almost certainly always be difficult and will be required only rarely, but even reference methods will not be easy to set up and are likely to prove uneconomic to keep running for individual laboratories to be able to do their own assays as required. Therefore centers need to be designated to carry out certain assays on a national and international basis.