THE TRANSFERABILITY OF A CANDIDATE REFERENCE METHOD FOR DETERMINATIONOF CREATININE IN SERUM

We developed a candidate reference method for the determination of cre atinine in serum. For the acceptance of a reference method it is impor tant that it be rigorously validated against a definitive method and t hat the method can be transferred from one laboratory to another. This study focussed on the transferability and consisted of two parts: int roduction and familiarization with the method in four clinical chemist ry laboratories in the Netherlands, followed by independent measuremen ts of Standard Reference Material 909a2 and several commercial quality control materials provided with reference method values according to the protocol of the German Quality Assessment Organisation. The criter ion for judging transferability was the mean total error (%) of the fi ve sera used in the accuracy experiment. For creatinine we used a tota l error of < 2.2%. For Standard Reference Material 909a2 all four labo ratories were able to comply with this demand, while only two laborato ries met this requirement for the other four sera. The results for the Standard Reference Material 909a2 from the collaborating laboratories demonstrate that this candidate reference method can be successfully transferred without loss of precision and accuracy.