Glomerular filtration rate: which method should we measure in daily clinical practice?

In this study, we compared estimated glomerular filtration rate (eGFR) calculated with the formulas of Cockcroft-Gault (C&G), Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Mayo Clinic Quadratic (Mayo Q) and, GFR (mGFR) that was scintigraphically measured with creatinine clearance (CrCl) and technetium-99m diethylene triamine penta-acetic acid (99mTc-DTPA). Objective of this study was to define the correlations between the formulas, provide a reliable method for measurement and estimation of GFR in daily clinical practice and demonstrate the potential errors.

C&G, CKD-EPI, Mayo Q and MDRD eGFR of 84(37 males, 47 females) patients diagnosed with chronic kidney disease were calculated. Values of 99mTc-DTPA based on mGFR were compared with eGFR values of the formulas.

Significant correlations were found with the values of 99mTc-DTPA mGFR, CrCl, MDRD, CKD-EPI, Mayo Q and C&G eGFR. The highest correlation was found between LBM(lean body mass) corrected C&G, MDRD-6, Mayo Q and CKD-EPI eGFR. The best estimate was made with MDRD-6 in the cases with 99mTc-DTPA mGFR<30 mL/min/1.73 m(2) and with MDRD-4 in the cases with 99mTc-DTPA mGFR≥30 mL/min/1.73 m(2), while the worst estimate was made with uncorrected C&G formula in both groups.

All eGFR formulas can be used in daily clinical practice. However, using MDRD-6 in the cases with GFR<30 mL/min/1.73 m(2) and MDRD-4 in the cases with GFR≥30 mL/min/1.73m(2) as well as using LBM for C&G eGFR or correction according to LBM when AW (actual weight) is used, might provide a more accurate estimation.