Obtaining reference intervals traceable to reference measurement systems : it is possible, who is responsible, what is the strategy ?

An issue associated with standardization efforts is the need to develop useful reference intervals (RI). Lack of proper RI may hamper the implementation of standardization in Laboratory Medicine as standardization can modify analyte results and, without adequate RI, this can impair the result interpretation. Once defi ned, RI obtained with analytical procedures that produce results traceable to the corresponding reference system can be transferred among laboratories, providing that they use commercial assays that produce results traceable to the same reference system and populations have the same characteristics. Multicenter studies are needed for a robust defi nition of traceable RI, using experimental protocols that include well defi ned prerequisites. Particularly, employed methods must produce results that are traceable to the reference system for that specifi c analyte. Thus, the trueness of laboratories producing reference values should be verifi ed and, if necessary, experimental results corrected in accordance with correlation results with the selected reference. If requirements in the adoption of traceable RI are fulfi lled, the possibility of providing RI that are applicable to any laboratory, able to produce results traceable to the reference system, is realistic. The defi nition of traceable RI should hopefully cause the disappearance of different RI employed for the same analyte, providing more effective information to clinicians.