BACKGROUND: A proper measurement of renal function is important for diagnosis and stratification of kidney disease. Several methods have been used to predict glomerular filtration rate, however the results have been variable depending on the population studied. We aimed to compare the performances of 4 glomerular filtration rate tests with inulin clearance in patients with chronic renal insufficiency and in healthy subjects. METHODS: Inulin clearances performed in 51 individuals with stable renal function were selected. For each of them, we computed 4 estimates: the 24-hour creatinine clearance, technetium (99mTc-DTPA) clearance, Cockcroft-Gault and Levey formulas. Their respective performance was assessed by correlation (Pearson's correlation coefficient) and agreement (Bland and Altman method). RESULTS: Each glomerular filtration rate test closely correlated with inulin clearance. Nevertheless, all GFR tests displayed considerable lack of agreement with lower limits ranging from 15 to 42 ml / min, for comparison with inulin-technetium and inulin with Levey formula, respectively and upper limits of agreement that could range from 20 to 56 ml / min, for comparison with inulin-technetium and Inulin with Levey formula,respectively. CONCLUSION: The measurement of glomerular filtration rate determined via different methods shows a wide range of variation when compared with inulin clearance, which should be considered in daily clinical practice during the evaluation of renal function.
BACKGROUND: A proper measurement of renal function is important for diagnosis and stratification of kidney disease. Several methods have been used to predict glomerular filtration rate, however the results have been variable depending on the population studied. We aimed to compare the performances of 4 glomerular filtration rate tests with inulin clearance in patients with chronic renal insufficiency and in healthy subjects. METHODS: Inulin clearances performed in 51 individuals with stable renal function were selected. For each of them, we computed 4 estimates: the 24-hour creatinine clearance, technetium (99mTc-DTPA) clearance, Cockcroft-Gault and Levey formulas. Their respective performance was assessed by correlation (Pearson's correlation coefficient) and agreement (Bland and Altman method). RESULTS: Each glomerular filtration rate test closely correlated with inulin clearance. Nevertheless, all GFR tests displayed considerable lack of agreement with lower limits ranging from 15 to 42 ml / min, for comparison with inulin-technetium and inulin with Levey formula, respectively and upper limits of agreement that could range from 20 to 56 ml / min, for comparison with inulin-technetium and Inulin with Levey formula,respectively. CONCLUSION: The measurement of glomerular filtration rate determined via different methods shows a wide range of variation when compared with inulin clearance, which should be considered in daily clinical practice during the evaluation of renal function.