Establishing measurement traceability in clinical chemistry

Traceability is not really a new fundamental concept in the field of laboratory medicine. Many years before the concept traceability had been mentioned in general chemical metrology, reference measurement procedures and reference materials had been established in clinical chemistry. Some basic experimental work for the development of reference measurement procedures and reference materials had already been undertaken in expert laboratories. 

Though various methods for the determination of enzyme activity are used routinely in clinical laboratories, many of them are covered by patents, and the components of their test kits are not commercially available. In clinical chemistry, reference methods and certified enzyme reference materials (enzyme calibrators) for determination of activities of enzymes in human blood serum are recommended by international commissions (ISOTC/212, International Federation of Clinical Chemistry IFCC, Institute for Reference Materials and Measurements EU, etc.) at present for improved accuracy and establishment of traceability chains of the enzyme measurement system. By using these reference materials, the inaccuracy (imprecision between laboratories) has been minimized to within several per cent in several enzymes, such as lactate dehydrogenase (LDH) (EC 1.1.1.27), y-glutamyltrans-peptidase (y-GT) (EC 2.3.2.2), alanine aminotransferase (ALT) (EC 2.6.1.2), creatine kinase (CK) (EC 2.7.3.2), alkaline phosphatase (ALP) (EC 3.1.3.1), acid phosphatase (EC 3.1.3.2), and a-amylase (AMY)... 

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