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A new reference material for C-reactive protein

Nov 07 2011

C-reactive protein (CRP) is one of the most important analytes in clinical chemistry. It is a very sensitive marker of inflammation and tissue damage. Routine clinical uses of CRP results include the diagnosis of bacterial and viral infections, the assessment of disease activity in inflammatory conditions like rheumatoid arthritis, and the determination of the long-term risk of cardiovascular disease and heart attacks.  

The Institute for Reference Materials and Measurements (IRMM) has released a new reference material certified for CRP. The reference material, ERM-DA474/IFCC, is the successor of ERM-DA472/IFCC and ERM-DA470, which were until recently used worldwide as the standard for CRP. These materials were on such a high demand that the production of a replacement was required. The new material will ensure continuity in the standardisation of CRP, which is crucial in clinical chemistry. It makes it possible for laboratories worldwide to use common reference ranges, and to compare results over time and between hospitals and countries.

The reference material ERM-DA474/IFCC is intended to be used to assign values to calibrators that are an integral part of in vitro diagnostic medical devices (IVD). The EU Directive on In Vitro Diagnostic Medical Devices (IVD-MD) (Directive 98/79/EC) requires traceability of calibrants and control materials to reference measurement procedures and/or reference materials of higher order. The International Federation of Clinical Chemistry (IFCC), which actively supports standardisation in clinical chemistry, has collaborated with IRMM on the development of ERM-DA474/IFCC.

The ERM-DA474/IFCC was produced from serum from blood collected in 4 blood collection centres according to a well-controlled procedure ensuring that it was obtained from healthy donors and that ERM-DA474/IFCC is most suited for the IVD devices currently available. The material was characterized using the reference material ERM-DA470 as a calibrant. For the production ERM-DA474/IFCC intensive research has been carried out on all stages of its development, from the effect of the processing on the physicochemical characteristics of the proteins to the validity of the metrological traceability chain and the commutability of the final material. These efforts have led to a different and optimised formulation of the material (e.g., liquid frozen instead of lyophilised, addition of calcium chloride), ensuring that the CRP is behaving like the protein in fresh patient samples.

The preparation of the material and its characterization are described in a comprehensive certification report, which is available together with the certificate.

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