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.