accuracy of modification of diet for renal disease and cockcroft-gault equations as compared to the radioisotope double sample method: a study in patients with acute renal failure

introduction: we intended to assess the accuracy of re-expressed modification of diet for renal disease (mdrd) and cockcroft-gault (cg) equations to estimate glomerular filtration rate (gfr) in chronic kidney disease in two different etiologies of acute renal failure (arf): acute tubular necrosis (atn) and acute glomerulonephritis (agn). methods: patients admitted for arf or the patients complicated with arf during the course of their hospitalization were enrolled to the study (n=21; 14 females and 7 males; 11 atn and 12 agn). when the plasma creatinine reached a steady state (dpsm) using 99mtc-dtpa. gfr was also estimated by mdrd (gfrmdrd) and cg (gfrcg) equations. results: the patients aged 44.8±19.5 years and weighted 67.8±10.7kg. gfrdpsm (32.9±14.7 ml/min) was statistically different from the gfrmdrd (11.6±8.2 ml/min; pcg was lower than gfrdpsm in patients with either atn (16.5±12.5ml/min and pdpsm and gfrmdrd (r=0.34; p=0.13) but gfrdpsm and gfrcg values were correlated (r=0.48; p=0.03). out of subjects with gfrdpsm >30, 92.3% had gfrmdrdcg conclusion: our results indicate that mdrd and cg equations were substantially inaccurate in patients with arf.   more precise methods of gfr evaluation is recommended in these patients.