Assessment of the Trueness and Inter-Laboratory Precision of Routine Uric Acid Assays Using 4 Frozen Pooled Serum Samples Measured by the Japan Society of Clinical Chemistry's HPLC Method

BACKGROUND Reference procedures are required for evaluating the accuracy of routine analytical systems for uric acid (UA). External quality assessment (EQA) for UA has only been conducted with quality controls in China, and the results have not been published. This study was designed to investigate both the trueness and inter-laboratory precision of UA measurements among routine analytical systems using a candidate reference method. METHODS We performed the HPLC method recommended by the Japan Society of Clinical Chemistry (JSCC). Next, we evaluated its analytical performance and validated its trueness. The performance of 4 routine analytical systems (5 instruments per system, n=20) for UA was assessed by using 4 frozen pooled serum samples measured by the HPLC method according to biologically relevant quality goals. RESULTS Within-run, between-run, inter-day, and total CV of the method were less than 0.3%, 0.4%, 1.8%, and 2.6%, respectively. The UA measurements were consistent with the target values of standard reference material (SRM) 909b, the sixth ring trial for Reference Laboratories (RELA-2008) specimen, and national primary reference materials. The 4 frozen pooled serum samples were homogeneous, stable, and commutable. All routine systems achieved the desirable performance goal (total error <11.9%). CONCLUSIONS We successfully reproduced the JSCC's HPLC method, which was simple, specific, precise, and accurate. We recommend this method as a reference method for UA measurement in human serum. Four routine analytical systems for UA measurement had acceptable traceability, and their UA results showed good concordance.