|It is important for clinical laboratory results to be comparable within and among laboratories. Comparability can be reached when common reference systems are established. Reference measurement procedures (RMP), important components of a reference system, must be traceable to international standards. In order for a mass spectrometric method to be called a RMP, it must be carefully investigated and its uncertainty of measurement known. It’s traceability to higher order standards must also be well-established. The Joint Committee for Traceability in Laboratory Medicine was formed to identify resources that can be used by manufacturers to establish traceability to higher order standards.