Función renal basal en pediatría: correlación de métodos que dependen de la recogida de orina de 24h con otros más sencillos que no requieren orina minutada / 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

INTRODUCCIÓN: En la práctica diaria es necesario disponer de métodos rápidos, sencillos y accesibles para valorar adecuadamente la función renal. Los objetivos fueron: 1) Cuantificar la relación y concordancia de la tasa de filtración glomerular (FG) calculada mediante el aclaramiento de creatinina en orina de 24 h (CCr) y la fórmula de Schwartz (FS) original y la FS modificada. 2) Relacionar la eliminación urinaria de sustancias que dependen del volumen de orina expulsada en una unidad de tiempo con otros parámetros que se calculan midiendo la concentración de estas sustancias en sangre y en orina. MATERIAL Y MÉTODOS: El estudio incluyó 401 niños sanos de 3-14 años (187 hombres y 214 mujeres). El análisis entre las variables se realizó mediante el coeficiente de correlación de Pearson y el coeficiente de concordancia intraclase (CCI) tipo consistencia. RESULTADOS: La correlación entre los valores de CCr y FS original (medición de creatinina no estandarizada) fue r = 0,58 (p < 0,001) y la concordancia, CCI = 0,74. La correlación entre las cifras de CCr y FS modificada (medición de creatinina estandarizada) fue r = 0,68 (p < 0,001) y la concordancia, CCI = 0,78. Existía una correlación muy significativa entre la eliminación de sodio en orina de 24 h (mEq/kg/24 h) y la excreción-fraccional-Na (EFNa): r = 0,8 (p < 0,001).También entre la eliminación de potasio en 24 h (mEq/kg/24 h) y EFK: r = 0,78 (p < 0,001). Entre la proteinuria (mg/m2/h) y el cociente proteína/creatinina urinario: r = 0,85 (p < 0,001). Y entre el volumen urinario (ml/min/1,73 m2) y el volumen % FG: r = 0,88 (p < 0,001). CONCLUSIONES: Estas ecuaciones proporcionan una valiosa información del estado de la función renal basal sin tener que recurrir a la orina minutada

INTRODUCTION: 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 24 h 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. MATERIAL AND METHODS: 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). RESULTS: 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 24 h urine (mEq/kg/24 h) 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). CONCLUSIONS: These equations provide valuable information of the state of the basal renal function without having to use a timed urine

[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]. / Función renal basal en pediatría: correlación de métodos que dependen de la recogida de orina de 24h con otros más sencillos que no requieren orina minutada.

INTRODUCTION: 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. MATERIAL AND METHODS: 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). RESULTS: 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). CONCLUSIONS: These equations provide valuable information of the state of the basal renal function without having to use a timed urine.

Physicochemical factors of the urine of children with hypercalciuria. / Características de los factores fisicoquímicos que componen la orina de los niños con hipercalciuria.

OBJECTIVE: Hypercalciuria is a common lithogenic risk factor. The aim of this study was, first, to study the characteristics of urine biochemical factors of children with hypercalciuria (HC) and compare them with those of children without hypercalciuria. Second, to analyze the differences between children with HC and lithiasis (HCL) and children with HC and no lithiasis (HCNL). METHODS: The sample was composed by 111 cases with HC, divided into 2 groups: HCNL group, consisting of 93 cases with no personal history of kidney stones, and HCL group, 18 cases with personal history of kidney stones. As a cohort control group, 113 healthy children were used. Creatinine, urea, sodium, potassium, chlorine, uric acid, calcium, phosphorus, magnesium and osmolality: blood and 24-hour urine following parameters were determined. Oxalate and citrate were determined in urine. RESULTS: The mean values of natriuresis, uricosuria, phosphaturia, magnesuria, citraturia, calcium oxalate and calcium phosphate saturation were higher in HCNL than in control group. The HCL group had phosphaturia, calcium oxalate and calcium phosphate saturations more elevated compared with the control group. There were no significant differences in urinary excretion of various parameters when the groups HCL and HCNL were compared. CONCLUSIONS: Our results show that children with hypercalciuria without lithiasis associated show an increase in natriuresis, phosphaturia, uricosuria, magnesuria and citraturia. We found no differences between these urinary abnormalities when compared hypercalciuric children without lithiasis with those with hypercalciuria and urolithiasis.

Características de los factores fisicoquímicos que componen la orina de los niños con hipercalciuria / Characteristics of the physicochemical factors that compound the urine of children with hypercalciuria

OBJETIVO: La hipercalciuria constituye un factor de riesgo litógeno frecuente. El objetivo de este estudio ha sido, en primer lugar, examinar las características de los factores bioquímicos que componen la orina de los niños con hipercalciuria (HC) y compararlas con las de niños normales. En segundo lugar, analizar las diferencias que presentan los niños con hipercalciuria y litiasis (HCL) de los niños con hipercalciuria sin litiasis (HSL) MÉTODOS: Muestra constituida por 111 casos con HC, divididos en 2 grupos: grupo HSL, compuesto por 93 casos sin historia personal de litiasis renal, grupo HCL, 18 casos con historia personal de litiasis renal. Como grupo control se utilizó una cohorte de 113 niños sanos. En sangre y en orina de 24 horas se determinaron los siguientes parámetros: creatinina, urea, sodio, potasio, cloro, ácido úrico, calcio, fósforo, magnesio y osmolalidad. En la orina se determinó oxalato y citrato. RESULTADOS: En comparación con el grupo control, los valores medios de la natriuresis, uricosuria, fosfaturia, magnesuria, citraturia, saturación de sales oxalato cálcico y saturación de fosfato cálcico estaban más elevados en las HSL. El grupo HCL presentaba la fosfaturia, saturación de oxalato cálcico y fosfato cálcico más elevadas en comparación con el grupo control. No había diferencias significativas en la excreción urinaria de los distintos parámetros cuando se compararon los grupos HSL y HCL. CONCLUSIONES: Nuestros resultados muestran que en los niños con hipercalciuria sin litiasis asociada existe una elevación en la excreción renal de sodio, ácido úrico, magnesio, y citrato. No encontramos diferencias entre estas anomalías urinarias cuando comparamos los casos con hipercalciuria sin litiasis de aquellos que presentan hipercalciuria y litiasis asociada

OBJECTIVE: Hypercalciuria is a common lithogenic risk factor. The aim of this study was, first, to study the characteristics of urine biochemical factors of children with hypercalciuria (HC) and compare them with those of children without hypercalciuria. Second, to analyze the differences between children with HC and lithiasis (HCL) and children with HC and no lithiasis (HCNL). METHODS: The sample was composed by 111 cases with HC, divided into 2 groups: HCNL group, consisting of 93 cases with no personal history of kidney stones, and HCL group, 18 cases with personal history of kidney stones. As a cohort control group, 113 healthy children were used. Creatinine, urea, sodium, potassium, chlorine, uric acid, calcium, phosphorus, magnesium and osmolality: blood and 24-hour urine following parameters were determined. Oxalate and citrate were determined in urine. RESULTS: The mean values of natriuresis, uricosuria, phosphaturia, magnesuria, citraturia, calcium oxalate and calcium phosphate saturation were higher in HCNL than in control group. The HCL group had phosphaturia, calcium oxalate and calcium phosphate saturations more elevated compared with the control group. There were no significant differences in urinary excretion of various parameters when the groups HCL and HCNL were compared. CONCLUSIONS: Our results show that children with hypercalciuria without lithiasis associated show an increase in natriuresis, phosphaturia, uricosuria, magnesuria and citraturia. We found no differences between these urinary abnormalities when compared hypercalciuric children without lithiasis with those with hypercalciuria and urolithiasis