Standardization of serum creatinine measurement: theory and practice.

Chronic kidney disease (CKD) is a major global public health problem. The best indicator of kidney function is considered to be the glomerular filtration rate (GFR), the rate that blood is filtered at the glomerulus. Currently, it is recommended that GFR be estimated using the estimating equation developed from the Modification of Diet in Renal Disease (MDRD) Study. To utilize the MDRD equation effectively requires reliable serum creatinine measurement. Understanding by laboratories world-wide of the importance of reliable serum creatinine measurements in GFR estimation and of factors that may affect creatinine measurement is critical to ongoing global public health efforts to increase the identification of patients with CKD. Serum creatinine assays must be properly calibrated and traceable to a high-order reference system in order to eliminate or significantly reduce variation among laboratories. If properly standardized world-wide, serum creatinine results can be used reliably to achieve universal implementation of GFR reporting as part of the global effort to diagnose and treat CKD.