The renal function as assessed by 99mTc-DTPA renal dynamic imaging and Cockcroft-Gault formula: a comparison study

Objective To evaluate the difference of the glomerular filtration rate (GFR) estimated by99mTc-DTPA renal dynamic imaging (gGFR) and Cockcroft-Gault (C-G) formula(eGFR), and the consistency in the staging of the chronic kidney disease patients. Methods gGFR and eGFR were calculated from the data of 945 chronic kidney disease patients who underwent the dynamic renal imaging. Wilcoxon test was performed to determine the difference of the two and the Spearman test for the correlation. Kappa test was used to evaluate the consistency of the staging of the patients, according to the gGFR and eGFR respectively. Results (1) The global eGFR (median 51.8)was significantly higher than gGFR(median 44.6),Z=-12.53,P<0.001; (2) there was a strong correlation between gGFR and eGFR (r=0.719,P<0.001); (3) the patients were divided into 3 stages (compensatory stage, moderately decreased stage and severely decreased stage ) according to eGFR and gGFR respectively, the global coincidence rate was 63.3% (598/945) with moderate consistency (Kappa=0.405,P<0.001); (4) when the patients were divided into 5 stages according to the gGFR, the serum creatinine value showed significant difference between every two stages (P<0.001) except stage1 and 2 (Z=-1.844,P=0.065), and the creatinine value increased as the stage going up. Conclusion There was a strong correlation between the GFR value estimated by99mTc-DTPA renal dynamic imaging and C-G formula, and a moderate consistency in the staging of the chronic renal disease patients. The two methods are complementary with each other and should be comprehensively utilized to accurately assess the renal function. Key words: Glomerular filtration rate; Renal fuction; DTPA