Comparison of methods of estimating creatinine clearance in children

Abstract

The accuracy of seven previously available and two new methods of estimating creatinine clearance (Clcr) from serum creatinine (Scr) and other patient variables was studied in pediatric patients. The medical records of 122 patients, aged 1--18 years, who had one or more 24-hour urine creatinines determined were reviewed; 158 determinations were studied. Equations for estimating Clcr based on patients' Scr, age, height, total body mass (TBM), adjusted body mass (ABM), and body surface area (and derivatives of these variables) were analyzed by correlation and regression analysis. Of the two derived equations, the one based on height and Scr was the simplest and most accurate; a nomogram for this equation is presented. The correlation coefficient for this derived equation (r = 0.802) was equivalent to that found for the best of the seven published methods (Method 7, based on Scr and height). Substitution of ABM for TBM in the published methods reduced the mean differences between predicted and measured Clcr. The derived equation based on Scr and height appears to be clinically useful in predicting Clcr in children but further study is required to ascertain whether it is generally more accurate than Method 7.