Milestones in Kidney Function Testing: Reflecting on the Journey Toward Serum Creatinine Measurement Standardization and Its Impact on Chronic Kidney Disease Diagnosis and Management

The global creatinine standardization initiative, driven by the NKDEP Laboratory Working Group, has dramatically reduced intermethod bias in serum creatinine measurement procedures, vastly improving the reliability of eGFR. While the metrologic traceability of calibration for creatinine measurement is now harmonized, challenges with analytical specificity, particularly for Jaffe-based methods, remain. The success of creatinine standardization serves as an important model for ongoing efforts to harmonize cystatin C and urine albumin measurements, ultimately leading to more accurate, equitable, and standardized care for patients with or at risk for CKD.