Implementation of reference systems in laboratory medicine.

In laboratory medicine, meaningful measurements are essential for the diagnosis, risk assessment, treatment, and follow-up of patients; therefore, methods applied in diagnostic measurements must be accurate, precise, specific, and comparable among laboratories (1). A given analytical measurement has only one true result, and the reliability of a measurement lies both in the result obtained and in the performance of a well-defined measurement procedure. Inadequate or incorrect analytical performance has consequences for the patient, the clinician, and the healthcare system. Poor-quality laboratory results may lead to incorrect interpretation by the physician, to a wrong diagnosis, and hence to treatment that impairs, or at least does not help, the patient’s situation. Measurement procedures in laboratory medicine should not be based on consensus but must follow the established rules of metrology as outlined in the International Vocabulary of Basic and General Terms in Metrology (VIM) (2). According to VIM, metrology includes all aspects of measurements in whatever fields of science or technology they occur. One key element of metrology is the traceability of a test result to the International System (SI), which ensures comparable results for different measurements of the same analyte in the same sample. “Traceability” is defined as the property of the result related to national or international standards through an unbroken chain of comparisons, each of which has stated uncertainties (2). The importance of these metrologic principles is described in an International Organization for Standardization (ISO)/European Committee for Standardization (CEN) standard (3). These rules must be followed if results of diagnostic measurements are to be comparable and true wherever in the world they are performed. Given the increased mobility of patients, comparable (true) test results are essential for a rational and cost-effective diagnostic approach. To reach these goals, international and regional organizations such as the ISO, the CEN, …