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A comparison between estimates of GFR using [99m– Tc]DTPA clearance and the approximation of Cockcroft and Gault
Author(s) -
Cochran M.,
John A. St
Publication year - 1993
Publication title -
australian and new zealand journal of medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.596
H-Index - 70
eISSN - 1445-5994
pISSN - 0004-8291
DOI - 10.1111/j.1445-5994.1993.tb01836.x
Subject(s) - renal function , plasma clearance , clearance rate , medicine , clearance , urology , body weight , metabolic clearance rate , confidence interval , nuclear medicine , endocrinology , pharmacokinetics
Background: The formula of Cockcroft and Gault, relating age, weight, sex and plasma creatinine is widely used to estimate glomerular function. Its ability to predict [ 99m Tc]DTPA clearance, an accepted measure of GFR, is therefore of interest. Aim: To test prospectively the reliability of the formula in predicting the [ 99m Tc]DTPA clearance in subjects with normal and sub‐normal renal function. Methods: The 24 hour creatinine clearance (Ccr), the derived clearance using the formula (C der ), and the [ 99m Tc]DTPA clearance have been compared in 47 male and 47 female subjects, aged between 15 and 71 years. Obese and non‐obese subjects (males >90 kg, females >80 kg body weight) were considered separately. Results: Across the range of [ 99m Tc]DTPA clearance studied (14 to 125 mL/minute), in non‐obese subjects, both Ccr and C der were correlated similarly with [ 99m Tc]DTPA clearance in males and females. In obese subjects as a group, C der was also closely correlated with [ 99m Tc]DTPA clearance but the scatter of data was wider. Among non‐obese subjects, correlations were high between either Ccr or C der and [ 99m Tc]DTPA clearance values < 101 mL/minute but were not significant at [ 99m Tc]DTPA clearance values > 100 mL/minute. For [ 99m Tc]DTPA clearance values between 14 and 100 mL/minute, C der was a more direct and more precise predictor of [ 99m Tc]DTPA clearance [DTPA clearance = 1.01(C der ) + 2.34, with 95% confidence limits of ± 18 mL/minute] than of Ccr [Ccr= 1.34(C der C)‐ 10.86, confidence limits ±28 mL/minute]. Conclusion : For very mild through to moderate renal failure, the formula of Cockcroft and Gault can evidently be used as a reasonable estimate of GFR. (Aust NZ J Med 1993; 23: 494–497.)