A reference system for urinary albumin: Current status

Background: Increased urinary excretion of albumin reflects kidney damage and is a recognized risk factor for progression of renal and cardiovascular disease. Considerable inter-method differences have been reported for both albumin and creatinine measurement results, and therefore the albumin-to-creatinine ratio. Measurement accuracy is unknown and there are no independent reference measurement procedures for albumin and no reference materials for either measurand in urine. Methods: The National Kidney Disease Education Program (NKDEP) Laboratory Working Group and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) have initiated joint projects to facilitate standardization of urinary albumin and creatinine measurement. Results: A candidate LC-MS/MS reference measurement procedure for urinary albumin and candidate reference materials for urinary albumin and creatinine has been developed. The status of validations of these reference system components is reported. Conclusions: The development of certified reference materials and reference measurement procedures for urinary albumin will enable standardization of this important measurand.