Comparison of Various Methods for Estimating Glomerular Filtration Rate in Patients with Chronic Kidney Disease

Kim, Dong Hyun; Kang, Shin Wook; Ko, Kwang Il; Kim, Chan Ho; Lee, Ju Hyun; Lee, Jin Ha; Kim, Eun Young; Park, Jung Tak; Chang, Tae Ik; Kim, Hyun Wook; Park, Sun Young; Chang, Jae Hyun; Kim, Dong Ki; Yoo, Tae Hyun; Han, Dae Suk

Abstract

PURPOSE: Several methods are used to estimate glomerular filtration rate (GFR), but there are limitations in each method. We investigated the variation in GFR measured by different methods in patients with chronic kidney disease (CKD).
METHODS
549 patients with CKD stages 2-5, who underwent creatinine clearance (Ccr) and (99m)Tc-DTPA renal scan, were enrolled. GFR was calculated by using Cockcroft-Gault equation (CG-GFR) and MDRD equation (MDRD-GFR). The correlations between MDRD-GFR and GFR estimated by other methods were analyzed according to CKD stages and age groups (<40, 40-59, and > or = 60 years).
RESULTS
The mean age of patients was 55+/-19 year (male 60%). CG-GFR, Ccr, and estimated GFR by (99m)Tc-DTPA renal scan (DTPA-GFR) correlated significantly with MDRD-GFR in all CKD stages and all age groups (p<0.01). Compared to patients with stages 2-4 CKD, however, the possibilities of CGGFR, Ccr, and DTPA-GFR to be within 30% of MDRD-GFR were significantly lower in stage 5 CKD patients (p<0.05). In addition, the ratio of DTPA-GFR/MDRD-GFR in stage 5 CKD patients was 2.24+/-1.40, indicating overestimation of DTPA-GFR in these patients. On the other hand, the accuracy of various GFR-estimating methods was higher in patients aged more than 60 years compared to the others.
CONCLUSION
CG-GFR, Ccr, and DTPA-GFR correlated significantly with MDRD-GFR, but there was a wide variation in GFR estimated by various methods. Therefore, a careful interpretation of estimation in GFR is needed according to the stage of CKD and the age of patients.