Urinary excretion of calcium, phosphate, magnesium, and uric acid in healthy infants and young children. Influence of feeding practices in early infancy.

BACKGROUND: Reference values for urinary calcium (Ca) and other solutes/creatinine (Cr) ratios in infants and young children are scarce. Its variation with type of lactation administered, breastfed (BF) or formula (F), is incompletely known. METHODS: A total of 511 spot urine samples from 136 children, aged 6 days to < 5 years, was collected. Urine was collected no fasting in infants < 18 months and first morning fasting in children aged 2.5-4 years. Urinary osmolality, Cr, urea, Ca, phosphate (P), magnesium (Mg), and uric acid (UA) were determined. Values are expressed as solute-to-Cr ratio. RESULTS: Urinary values were grouped according to the child's age: 6-17 days (G1), 1-5 months (G2), 6-12 months (G3), 13-18 months (G4), and 2.5-4 years (G5). G1 was excluded; Ca/Cr and UA/Cr (95th percentile) decreased with age (G2 vs. G5) from 1.64 to 0.39 and 2.33 to 0.83 mg/mg, respectively. The P/Cr median rises significantly with age from 0.31 (G2) to 1.66 mg/mg (G5). Mg/Cr was similar in all groups (median 0.20, 95th percentile 0.37 mg/mg). Ca/Cr (95th percentile) of BF infants was 1.80 mg/mg (< 3 months) and 1.63 mg/mg (3-5 months), much higher than F infants (0.93 and 0.90 mg/mg, respectively). P/Cr and P/Ca were lower in BF infants. CONCLUSIONS: Values for urinary Ca/Cr, P/Cr, Mg/Cr, and UA/Cr in infants and children < 5 years were updated. BF infants < 6 months showed higher Ca/Cr and lower P/Cr than F infants. New cutoff values to diagnose hypercalciuria in infants < 6 months, according to the type of lactation, are proposed.

Hipouricemia renal hereditaria tipo 1 y 2 en tres niños españoles. Revisión de casos pediátricos publicados / Hereditary renal hypouricemia type 1 and 2 in three Spanish children. Revision of published pediatric cases

La hipouricemia renal hereditaria es un trastorno genético, poco frecuente, causado por un defecto aislado en la reabsorción del ácido úrico a nivel del túbulo renal. Los pacientes presentan concentraciones séricas de ácido úrico inferiores a 2 mg/dl (119 micromol/L), y un incremento en la excreción fraccional de ácido úrico mayor del 10%. La mayoría son asintomáticos y se detectan accidentalmente, aunque pueden aparecer complicaciones como la nefrolitiasis, hematuria, daño renal agudo inducido por ejercicio físico o tras un episodio de deshidratación por gastroenteritis aguda, o el síndrome de encefalopatía posterior reversible. La hipouricemia renal hereditaria se confirma por el análisis molecular de los dos genes que codifican los transportadores de urato a nivel del túbulo renal. La hipouricemia renal tipo 1 (OMIM 220150) con pérdida de función en el gen SLC22A2 que codifica el transportador URAT1 y la hipouricemia renal tipo 2 (OMIM 612076) con mutaciones en el gen SLC2A9 que codifica el transportador GLUT9. Las formas más graves se producen en pacientes con mutaciones en el gen SLC2A9 en homocigosis. La mayoría de mutaciones se han descrito en adultos Japoneses, y sólo unos pocos casos en niños. Presentamos tres casos de niños españoles asintomáticos con hipouricemia renal confirmada genéticamente y realizamos revisión de los casos pediátricos con estudio genético, publicados en la literatura

Hereditary renal hypouricemia is a rare autosomal recessive genetic disorder that involves an isolated defect in uric acid reabsorption at the renal tubules. Patients present with serum uric acid concentrations of less than 2mg/dl (119 micromol/L) with increased fractional excretion above 10%. Most of the patients are asymptomatic and are detected incidentally. However, complications such us nephrolithiasis, hematuria, acute renal failure exercise-induced or after dehydration for acute gastroenteritis, or posterior reversible encephalopaty syndrome (PRES) may develop. Hereditary renal hypouricemia is confirmed by molecular genetic analysis of the two genes which codify the uric acid transport in the kidney tubules. The renal hypouricemia type 1 (OMIM 220150) is characterized by loss-of-function mutations in the SLC22A12 gene which encodes URAT 1 transporter, and the hypouricemia type 2 (OMIM 612076) is caused by defects in the SLC2A9 gene. Homozygous mutations of SLC2A9 cause the most severe forms of the disease. Most mutations have been identified in Japanese adults, and only a few in children. We describe three asyntomatic pediatric Spanish patients with renal hypouricemia, with genetic confirmation, and we make a revision of all of the pediatric cases with genetic study published in the literature

Hipouricemia renal hereditaria tipo 1 y 2 en tres niños españoles. Revisión de casos pediátricos publicados.

Hereditary renal hypouricemia is a rare autosomal recessive genetic disorder that involves an isolated defect in uric acid reabsorption at the renal tubules. Patients present with serum uric acid concentrations of less than 2mg/dl (119 micromol/L) with increased fractional excretion above 10%. Most of the patients are asymptomatic and are detected incidentally. However, complications such us nephrolithiasis, hematuria, acute renal failure exercise-induced or after dehydration for acute gastroenteritis, or posterior reversible encephalopaty syndrome (PRES) may develop. Hereditary renal hypouricemia is confirmed by molecular genetic analysis of the two genes which codify the uric acid transport in the kidney tubules. The renal hypouricemia type 1 (OMIM 220150) is characterized by loss-of-function mutations in the SLC22A12 gene which encodes URAT 1 transporter, and the hypouricemia type 2 (OMIM 612076) is caused by defects in the SLC2A9 gene. Homozygous mutations of SLC2A9 cause the most severe forms of the disease. Most mutations have been identified in Japanese adults, and only a few in children. We describe three asyntomatic pediatric Spanish patients with renal hypouricemia, with genetic confirmation, and we make a revision of all of the pediatric cases with genetic study published in the literature.

Factores predictivos de daño renal en la infección febril del tracto urinario. Utilidad de la procalcitonina / Predictive factors for kidney damage in febrile urinary tract infection. Usefulness of procalcitonin

Objetivo: Establecer la utilidad de la procalcitonina (PCT) y otros parámetros clínicos y analíticos como indicadores de daño renal agudo y permanente en niños tras una primera infección del tracto urinario (ITU) febril. Material y métodos: Estudio retrospectivo multicéntrico. Estudio estadístico: descriptivo, curvas ROC y regresión logística múltiple. Resultados: 219 pacientes, con edades entre 1 semana y 14 años (68 % menores de 1 año). Las medias de PCT fueron significativamente mayores en pacientes con pielonefritis aguda respecto a aquellos con DMSA agudo normal (4,8 frente a 1,44; p = 0,0001), sin alcanzar significación para DMSA tardío (6,5 frente a 5,05; p = 0,6). El área bajo la curva ROC de PCT fue 0,64 (IC 95 % 0,55-0,72) para daño renal agudo y 0,62 (IC 95 % 0,44-0,80) para permanente; con puntos de corte óptimos de 0,85 y 1,17 ng/ml. El análisis multivariante para daño renal agudo solo encontró correlación con PCT (odds ratio [OR] 1,2, IC 95 % 1,06-1,4; p = 0,005) y horas de fiebre (OR para < 6 h 0,4, IC 95 % 0,2-1,02; p = 0,05). En los pacientes con cicatriz, la OR para PCT fue 1,0 (IC 95 % 0,9-1,1; p = 0,6). Conclusiones: La PCT y la duración de la fiebre fueron los únicos parámetros que se asociaron de forma significativa a daño parenquimatoso agudo. No se observó relación estadísticamente significativa entre la PCT y la cicatriz renal (AU)

Objective: To establish the utility of procalcitonin (PCT) and other clinical and analytical parameters as markers of acute and permanent renal damage in children after a first febrile urinary tract infection (UTI). Methods: Retrospective multicentre study. Statistical study: descriptive, receiver operating characteristic (ROC) curves and multiple logistic regression. Results: 219 patients, aged between 1 week and 14 years (68% under 1 year). The mean PCT values were significantly higher in patients with acute pyelonephritis with respect to normal acute DMSA (4.8 vs 1.44; p=0.0001), without achieving that signification for late affected DMSA (6.5 vs 5.05; p=0.6). The area under the ROC curve for PCT was 0.64 (CI 95% 0.55-0.72) for acute renal damage, and 0.62 (CI 95% 0.44-0.80) for permanent damage, with optimum statistical cut-off values of 0.85 and 1.17ng/ml. Multivariate analysis for acute renal damage only found correlation with PCT (Odds Ratio [OR] 1.2 (CI 95% 1.06-1.4, p=0.005), and hours of fever (OR for less than 6 hours of fever 0.4 (CI 95% 0.2-1.02, p=0.05). In patients with renal scarring, PCT showed an OR 1.0 (CI 95% 0.9-1.1, p=0.6). Conclusions: PCT and the duration of fever were the only parameters statistically associated with early renal damage. PCT and renal scarring did not reach statistical significance (AU)

Predictive factors for kidney damage in febrile urinary tract infection. Usefulness of procalcitonin.

OBJECTIVE: To establish the utility of procalcitonin (PCT) and other clinical and analytical parameters as markers of acute and permanent renal damage in children after a first febrile urinary tract infection (UTI). METHODS: Retrospective multicentre study. Statistical study: descriptive, receiver operating characteristic (ROC) curves and multiple logistic regression. RESULTS: 219 patients, aged between 1 week and 14 years (68% under 1 year). The mean PCT values were significantly higher in patients with acute pyelonephritis with respect to normal acute DMSA (4.8 vs 1.44; p=0.0001), without achieving that signification for late affected DMSA (6.5 vs 5.05; p=0.6). The area under the ROC curve for PCT was 0.64 (CI 95% 0.55-0.72) for acute renal damage, and 0.62 (CI 95% 0.44-0.80) for permanent damage, with optimum statistical cut-off values of 0.85 and 1.17ng/ml. Multivariate analysis for acute renal damage only found correlation with PCT (Odds Ratio [OR] 1.2 (CI 95% 1.06-1.4, p=0.005), and hours of fever (OR for less than 6 hours of fever 0.4 (CI 95% 0.2-1.02, p=0.05). In patients with renal scarring, PCT showed an OR 1.0 (CI 95% 0.9-1.1, p=0.6). CONCLUSIONS: PCT and the duration of fever were the only parameters statistically associated with early renal damage. PCT and renal scarring did not reach statistical significance.