State of the art in trueness and interlaboratory harmonization for 10 analytes in general clinical chemistry.

CONTEXT Harmonization and standardization of results among different clinical laboratories is necessary for clinical practice guidelines to be established. OBJECTIVE To evaluate the state of the art in measuring 10 routine chemistry analytes. DESIGN A specimen prepared as off-the-clot pooled sera and 4 conventionally prepared specimens were sent to participants in the College of American Pathologists Chemistry Survey. Analyte concentrations were assigned by reference measurement procedures. PARTICIPANTS Approximately 6000 clinical laboratories. RESULTS For glucose, iron, potassium, and uric acid, more than 87.5% of peer groups meet the desirable bias goals based on biologic variability criteria. The remaining 6 analytes had less than 52% of peer groups that met the desirable bias criteria. CONCLUSIONS Routine measurement procedures for some analytes had acceptable traceability to reference systems. Conventionally prepared proficiency testing specimens were not adequately commutable with a fresh frozen specimen to be used to evaluate trueness of methods compared with a reference measurement procedure.