Basal renal function in paediatric patients: Correlation of methods that depend on a 24 h urine collection with simpler methods that do not require a timed urine

Introduction: In the daily practice it is necessary to have quick, easy and accesible methods to adequately assess the renal function. The objectives were: 1. Quantify the relationship and concordance of the glomerular filtration rate (FG) calculated by the clearance of creatinine in 24 h urine (CCr) and the original and modified Schwartz equation (SE). 2. Correlate urine elimination of substances that depend on the volume of excreted urine in a unit of time with other parameters that are calculated measuring the concentration of these substances in blood and urine. Materials and methods: The study included 401 healthy children in the ages between 3 to14 (187 male and 214 female). The analysis between the variables was carried out by Pearson’s correlation coeficient and the intraclass correlation coefficient. Results: The correlation between values of CCr and the original SE (non standardized creatinine measuring) was r = 0.58 (P