Traceability in laboratory medicine

Keywords Calibration hierarchy Comparability of results Joint Committee on Traceability in Laboratory Medicine Metrological traceability Reference examination system... 

A Symposium on Traceability in Laboratory Medicine, BIPM, 2002 06 09/1 1, called by Dr Terry J. Quinn, BIPM, and Professor Mathias M. M ller, IFCC, assembled some 60 delegates from Australia, Canada, Europe, Japan, South Africa, and United States. (The entities represented are indicated by an asterisk in Table 1.)... 

Traceability of examination results is necessary to ensure reliability and the spatio-temporal comparability which is increasingly needed in the health services. The required global multielement reference examination system hitherto has been provided in a piecemeal fashion, but with the newly established Joint Committee on Traceability in Laboratory Medicine (JCTLM), coordinating all stakeholders with CIPM/BIPM, IFCC, ILAC, and WHO in the lead, the sparse resources should be distributed in a prioritised and structured way. 

Standardization—reference systems—traceability in laboratory medicine... 

Joint Committee for Traceability in Laboratory Medicine (JCTLM) ... 

Abstract The concept of total allowable error , investigated by Westgard and co-workers over a quarter of a century for use in laboratory medicine, comprises bias as well as random elements. Yet, to minimize diagnostic misclassifi-cations, it is necessary to have spatio-temporal comparability of results. This requires trueness obtained through metrological traceability based on a calibration hierarchy. Hereby, the result is associated with a final uncertainty of measurement purged of known... 

It is relevant to ask how often the routine measurement procedures currently used in laboratory medicine provide results that are traceable to high-level calibrators and reference measurement procedures (Lequin personal communication). It turns out that primary reference measurement procedures and primary calibrators are only available for about 30 types of quantity such as blood plasma concentration of bilirubins, cholesterols and sodium ion. International reference measurement procedures from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and corresponding certified reference material from BCR are available for the catalytic activity concentration of a few enzymes such as alkaline phosphatase and creatine kinase in plasma. For another 25 types of quantity, such... 

In laboratory medicine more than 500 measurands are used for diagnosis and follow-up of patients [43, 44], At presence only some 100 are traceable to the SI as described in Table 1. The vast majority of measurement results are not traceable to the SI, but to arbitrary units,... 

The concept of measurement traceability provides probably the most important strategy to achieve standardisation in laboratory medicine aimed at comparable measurement results regardless of the method, the measurement procedure (test kit) and of the laboratory where the analyses are carried out. 

The complete traceability chain as presented here is valid only for those measurable quantities, which can have a value, expressed in SI units. When primary or secondary calibrators are not available the traceability chain for many measurands in laboratory medicine ends at a lower level, e.g. at the manufacturer s standing measurement procedure. In a situation where a manufacturer detects a new diagnostic marker and defines the measurable quantity by establishing a measurement procedure for this marker, the manufacturer s measurement procedure will form the top of the traceability chain. Nevertheless even in this simple situation the principles of the traceability concept are applicable. 

Method-dependent measurements can be grouped by sector. For example, in the clinical fields there are cases where some higher order reference materials are required for IVD methods, such as for determination of glucose in human serum. It is also required of reference laboratories in specific measurement methods. These issues are now under the responsibility of JCTLM (Joint Committee on the Traceability of Laboratory Medicine of CCQM). CENAM has developed a reference material for glucose and cholesterol determination in human serum, and certified by IDMS, which is under review by JCTLM for the use by reference laboratories in any country applying a reference method. 

Table 2 Groups in the International Federation of Clinical Chemistry and Laboratory Medicine related to various elements of metrological traceability...

Traceability in clinical chemistry/laboratory medicine (three contributions)... 

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. 

The beginnings of pharmacodynamics as a science is traceable to the efforts of Rudolf Buchheim (1820—1879), born in Saxony, the son of a physician. Four years after graduating in medicine, he was promoted to the rank of full professor at the (Baltic) University of Dorpat, where he established the World s first pharmacological laboratory and attracted many brilliant young men to work in it. In 1867, he transferred to a comparable position in Giessen (Germany), where he remained until his death from a stroke. 

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