ABSTRACT
Objective To find out whether the levels of serum creatinine and urea,creatinine clearance rate and GFR estimated by using different equations correlate with the exact measurement of GFR with ~(99m)Tc-DTPA in elderly patients with chronic kidney disease.Methods Renal function was determined by using ~(99m)Tc-DTPA technique in 83 elderly patients aged 65—96 years.Blood and urine tests were done at the same time.Estimated clearance was determined by using the equations of Cockcroft-Gauh,MDRD(modification of diet in renal disease)predigestion and MDRD seventh,and the correlation coefficients between the above parameters and ~(99m)Tc-GFR were determined.Veracity for the diagnosis of renal dysfunction was calculated by using receiver operating characteristic(ROC) curves.Results Cockcroft-Gault formula(r=0.833),MDRD predigestion formula(r=0.811), MDRD seventh formula(r=0.803),creatinine(r=-0.672),Ccr(r=0.632),urea(r=-0.612), and albumin(r=0.444)were correlated significantly with ~(99m)Tc-GFR in this sequence.If GFR 30, 40,50,60ml/min were defined respectively as renal impairment thresholds and areas under the curve (AUC)were compared,the best parameter for estimation of GFR was the Cockcroft-Gault formula. Then MDRD predigestion formula and MDRD seventh formula,creatinine and Ccr were less accurate in all different renal dysfunction thresholds.Conclusions The Cockcroft-Gault equation seems to be the best formula available for GFR estimation,the two equations of MDRD are the second,creatinine is the third,Ccr and urea are the last.