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An Pediatr (Barc). 2020 Feb;92(2):65-70. doi: 10.1016/j.anpedi.2019.08.005. Epub 2019 Oct 24.

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

[Article in Spanish]

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Sección de Nefrología Pediátrica, Hospital Universitario Donostia, San Sebastián, España. Electronic address:
Sección de Nefrología Pediátrica, Hospital Universitario Donostia, San Sebastián, España.



In daily clinical practice a quick, easy and accessible method is needed to adequately assess renal function. The objectives of this study were: 1. To quantify the relationship and concordance of the glomerular filtration rate (GF) calculated by the clearance of creatinine in 24h urine (CCr) and the original and modified Schwartz equation (SE); and 2. To correlate urine elimination of substances that depends 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.


The study included 401 healthy children with ages between 3 to 14 years (187 male and 214 female). The analysis between the variables was carried out using Pearson's correlation coefficient and the intraclass correlation coefficient (ICC).


The correlation between values of CCr and the original SE (non-standardised creatinine measurement) was r=0.58 (P<0.001) and the concordance, ICC=0.74. The correlation between CCr values and the modified SE (standardised creatinine measurement) was r=0.68 (P<.001), and the concordance ICC=0.78. There was a very significant correlation between the elimination of sodium in a 24h urine (mEq/kg/24h) and the Na-Fractional-Excretion (EFNa): r=0.8 (P<.001). There was a correlation between the potassium elimination in 24h (mEq/kg/24h) and EFK: r=0.85 (P<.001). Between volume/min/1.73m2 and the urine volume percent of GF was: r=0.88 (P<.001).


These equations provide valuable information of the state of the basal renal function without having to use a timed urine.


Glomerular filtration rate; Kidney function test; Niños; Paediatric; Potasio; Potassium; Pruebas de función renal; Sodio; Sodium; Tasa de filtración glomerular

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