American Association for Clinical Chemistry
Better health through laboratory medicine
Reporting Estimated GFR from Serum Creatinine: Recommendations from the Laboratory Working Group of the National Kidney Disease Education Program

May 2, 2006: W. Gregory Miller, PhD, DABCC, FACB

Developed in co-operation with the National Kidney Disease Education Program

AACC Statement on Estimated GFR Calculation

The goal of the National Kidney Disease Education Program (NKDEP) is to identify people with chronic kidney disease to provide early treatment to slow or prevent progression of the disease. Serum creatinine is a frequently ordered test that is difficult to interpret at the values associated with early chronic kidney disease. Reporting a GFR estimated from serum creatinine provides a better interpretation related to chronic kidney disease.

The Laboratory Working Group reviewed serum creatinine measurement and developed recommendations for reporting estimated GFR and to standardize and improve creatinine measurement. The current variability in serum creatinine measurement renders all estimating equations for GFR, including the MDRD study equation, less accurate in the normal and slightly elevated range of serum creatinine concentrations (<133 µmol/L, <1.5 mg/dl) which are most important for detecting chronic kidney disease (<60 mL/min/1.73 m2). Standardizing calibration of creatinine results to an isotope dilution mass spectrometry reference measurement procedure requires coordination by method manufacturers and clinical laboratories to use the correct MDRD equation to calculate GFR and to communicate associated clinical issues to clinical providers and pharmacists.