Commutability of the ERM-DA470k reference material for two assays measuring serum albumin using immunochemical principles.

The standardization of measurements is a high-priority in Laboratory Medicine; its purpose being to achieve closer comparability of results for the same analyte obtained using different commercial systems (1). The promotion of result traceability to available higher-order reference measurement procedures and reference materials is the recommended approach (2). A major prerequisite for guaranteeing comparability of results among different methods is the availability of suitable reference materials, appropriately and thoroughly defined by a set of characteristics (3, 4). Reference materials can be used for calibration of routine methods. However, when reference materials are intended for direct value assignment to manufacturer’s calibrators, they should be extensively investigated for commutability (5). The main serum proteins are among the best standardized analytes in clinical laboratories. In 1993, the Bureau Communautaire de Reference of European Commission released the certified reference material (CRM) 470 (later renamed to ERM-DA470), developed in collaboration with the IFCC, resulting in a highly significant reduction of the among-laboratory variance for most proteins (6, 7). The ERM-DA470k/IFCC is a new serum protein reference material prepared to replace ERM-DA470, and to ensure continuity of the standardization of serum protein measurements (8, 9). With regard to serum albumin, the availability of these serum protein reference materials, both including albumin in the list of certified proteins, together with immunochemical methods based on turbidimetry-nephelometry principles, recognized as reference measurement procedures by the Joint Committee on Traceability in Laboratory Medicine (JCTLM),