Abstract:

Objective To optimize serum uric acid reference measurement produce（reference method），and to provide a reference for the establishment of conventional systems. Methods The reference methods of serum uric acid recommended by American Association for Clinical Chemistry（AACC） were established and optimized（centrifugation for 40 min and recentrifugation for 15 min），and accuracy verification was performed by the National Institute of Standards and Technology（NIST）standard reference method（SRM） 909C and RELA20B，RELA21A. High，medium and low clinical residual serum samples were collected，and each concentration value was measured for precision verification. Totally，6 concentration gradients were configured for linear evaluation. The optimized reference method and clinical conventional method were used to measure 40 individual serum samples simultaneously，and the results of the 2 methods were analyzed by regression analysis. According to the Clinical and Laboratory Standards Insititute（CLSI） EP14-A3，interchangeability analysis of calibrators used in conventional methods was performed. Results The results of SRM 909C，RELA20B and RELA21A measured before and after the optimization of reference method were all within the equivalent limit of the International Federation of Clinical Chemistry and Laboratory Medicine（IFCC）（3.25%），and the results of SRM 909C before and after the optimization were also within the certificate range [（278.57±5.95） μmol/L]. After optimization，the repeatability precision was improved obviously. Although the repeatability precision was not improved obviously，the low-value precision was improved，and it met the precision requirement of laboratory [coefficient of variation（CV）<2%]. The optimized linear correlation（r²=0.999 9）was good，the slope was closer to 1，and the intercept was closer to 0. The expected biases of conventional method at medically determined levels 110，480 and 640 μmol/L were -15.86%，-2.03% and -1.01%，respectively. The 2 calibrators exceeded the 95% confidence interval，so there was no interchangeability between the reference method and the conventional method. Conclusions The optimized serum uric acid reference method has good precision and linear correlation，which can provide a reference for the establishment and traceability of clinical conventional measurement procedure.

Key words: Uric acid, Reference measurement proceduce, Optimization, Methodological comparison