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.

Raquitismo hipofosfatémico hereditario con hipercalciuria: a propósito de un caso / Hereditary hypophosphatemic rickets with hypercalciuria: Case report

Presentamos el caso clínico de un varón de 50 años de edad que consulta por presentar una enfermedad renal litiásica recidivante y una nefrocalcinosis. En la exploración clínica destacó una talla baja y un genu varo bilateral importante. Entre los datos bioquímicos se apreciaba una pérdida renal de fosfatos intensa con hipofosfatemia, una 25 OH vitamina D3 normal, una 1,25 OH2 vitamina D3 elevada y una hipercalciuria. La hormona paratiroidea (PTHi) se encontraba disminuida y en la ecografía renal se confirmó la existencia de una nefrocalcinosis bilateral grave, localizada en la médula renal. Además, se constató una insuficiencia renal crónica incipiente y una acidosis tubular renal incompleta, ambas secundarias a la nefrocalcinosis y no directamente relacionadas con la enfermedad basal. En el estudio molecular se encontró un cambio en homocigosis en el intrón 5 del gen SLC34A3 (NM_080877.2:c[448+5G>A]+[448+ 5G>A]). Sus tres hijos eran portadores de esta misma variante en heterocigosis y, aunque clínicamente estaban asintomáticos, dos de ellos tenían una hipercalciuria. Todos estos datos parecían (..) (AU)

We report a case of a male aged 50 years who consulted for renal disease recurrent lithiasis and nephrocalcinosis. The clinical examination showed external signs of rickets/osteomalacia and biochemical data as well as a severe loss of renal phosphate with hypophosphatemia, normal 25 OH vitamin D, high 1,25 OH vitamin D and hypercalciuria. Parathyroid hormone was low and renal ultrasound confirmed the existence of severe bilateral medullary nephrocalcinosis. They also found incipient chronic renal failure and incomplete renal tubular acidosis, both secondary to nephrocalcinosis and unrelated to the underlying disease. The molecular study found a change in homozygosity in intron 5 of gene SLC34A3 (NM_080877.2:c[ 448 +5G>A] + [ 448 +5G>A] ). His three children were carriers of the same variant in heterozygosis and although they were clinically asymptomatic two of them had hypercalciuria. All these data suggest that the patient had hereditary hypophosphataemic rickets with hypercalciuria (HHRH) secondary to an alteration in the sodium dependent phosphate cotransporter located in proximal tubule (NaPi-IIc). The HHRH is transmitted by autosomal recessive inheritance and is an extremely rare form of hypophosphatemic rickets. The diagnosis and treatment are essential to prevent bone sequelae of rickets and nephrocalcinosis. A correct differential diagnosis with other forms of hypophosphatemic rickets has implications on the treatment, as the management based only on phosphorus supplementation usually corrects all clinical and biochemical abnormalities, except for the loss of phosphorus in the urine. The exogenous supply of calcitriol, as advised in other hypophosphatemic rickets, may induce renal calcium deposits and nephrocalcinosis and worsens the prognosis (AU)

Hereditary hypophosphatemic rickets with hypercalciuria: case report.

We report a case of a male aged 50 years who consulted for renal disease recurrent lithiasis and nephrocalcinosis. The clinical examination showed external signs of rickets/osteomalacia and biochemical data as well as a severe loss of renal phosphate with hypophosphatemia, normal 25 OH vitamin D, high 1,25 OH vitamin D and hypercalciuria. Parathyroid hormone was low and renal ultrasound confirmed the existence of severe bilateral medullary nephrocalcinosis. They also found incipient chronic renal failure and incomplete renal tubular acidosis, both secondary to nephrocalcinosis and unrelated to the underlying disease. The molecular study found a change in homozygosity in intron 5 of gene SLC34A3 (NM_080877.2:c[ 448 +5G>A] + [ 448 +5G>A] ). His three children were carriers of the same variant in heterozygosis and although they were clinically asymptomatic two of them had hypercalciuria. All these data suggest that the patient had hereditary hypophosphataemic rickets with hypercalciuria (HHRH) secondary to an alteration in the sodium dependent phosphate cotransporter located in proximal tubule (NaPi-IIc). The HHRH is transmitted by autosomal recessive inheritance and is an extremely rare form of hypophosphatemic rickets. The diagnosis and treatment are essential to prevent bone sequelae of rickets and nephrocalcinosis. A correct differential diagnosis with other forms of hypophosphatemic rickets has implications on the treatment, as the management based only on phosphorus supplementation usually corrects all clinical and biochemical abnormalities, except for the loss of phosphorus in the urine. The exogenous supply of calcitriol, as advised in other hypophosphatemic rickets, may induce renal calcium deposits and nephrocalcinosis and worsens the prognosis.