Reflux nephropathy and scarring nephropathy: So close and yet so different.

OBJECTIVES: Reflux nephropathy is a radiologic condition commonly used to express the existence of renal morphological lesions in patients who have or had vesicoureteral reflux (VUR). This morphological concept is used based on the image data collected, without conducting basic complementary renal function studies. The present study was designed to demonstrate that patients with active VUR present different functional renal alterations from those shown by patients with disappeared VUR. METHODS: Longitudinal descriptive retrospective analysis including 89 children (46M, 43F) with VUR diagnosis through a standard voiding cystourethrogram (VCUG). The basic renal function tests collected were the maximum urinary osmolality (UOsm) and the urinary albumin/creatinine and NAG/creatinine ratios. The data collected corresponded to two moments, when VUR was diagnosed and when it had already disappeared. RESULTS: Quantitative differences were verified in the three functional parameters when comparing those corresponding to both moments of the study. In the qualitative analysis, in relation to the intensity of the VUR, differences were observed in UOsm at diagnosis and in the albumin/creatinine ratio once the VUR had cured. At this last moment, a significant increase in the albumin/creatinine ratio was observed in patients with loss of renal parenchyma in relation to those without residual morphological lesions. CONCLUSIONS: Concentrating ability defect is the most frequent finding in children with active reflux (true reflux nephropathy), whereas the most frequent functional disturbance found, once VUR has cured, is an increase in urinary albumin excretion, related to parenchymal damage. The term dysplastic-scarring nephropathy, could be more appropriate for patients with residual morphological lesions and impaired renal function, once VUR is cured.

Nefropatía de reflujo y nefropatía cicatricial. Dos entidades tan cercanas pero funcionalmente tan distintas / Reflux nephropathy and scarring nephropathy: So close and yet so different

Objetivo: La nefropatía de reflujo es el término radiológico que se utilizó para expresar la existencia de lesiones morfológicas renales en pacientes con reflujo vesicoureteral (RVU). Este concepto morfológico se acuñó a partir de los datos de imagen recogidos, aunque sin realizar estudios complementarios básicos de función renal. Este estudio se diseñó para demostrar que las pruebas de función renal básicas muestran resultados distintos en presencia de RVU activo y una vez desaparecido. Pacientes y métodos: Estudio descriptivo retrospectivo longitudinal en el que se incluyeron 89niños (46V, 43M) con RVU diagnosticado mediante cistouretrografía miccional seriada. Las pruebas básicas de función renal recogidas fueron la osmolalidad urinaria máxima (UOsm) y los cocientes urinarios albúmina/creatinina y NAG/creatinina. Los datos acopiados correspondían a dos momentos: al diagnosticarse el RVU y cuando ya se había curado. Resultados: Se comprobaron diferencias cuantitativas en los tres parámetros funcionales al comparar los correspondientes a ambos momentos del estudio. En el análisis cualitativo, en relación con la intensidad del RVU, se apreciaron diferencias en UOsm al diagnóstico y en el cociente albúmina/creatinina una vez desaparecido el RVU. En este último momento se observó un aumento significativo en el cociente albúmina/creatinina en los pacientes con pérdida de parénquima renal en relación con aquellos sin lesiones morfológicas residuales. (AU)

Objectives: Reflux nephropathy is a radiologic condition commonly used to express the existence of renal morphological lesions in patients who have or had vesicoureteral reflux (VUR). This morphological concept is used based on the image data collected, without conducting basic complementary renal function studies. The present study was designed to demonstrate that patients with active VUR present different functional renal alterations from those shown by patients with disappeared VUR. Patients and methods: Longitudinal descriptive retrospective analysis including 89 children (46M, 43F) with VUR diagnosis through a standard voiding cystourethrogram (VCUG). The basic renal function tests collected were the maximum urinary osmolality (UOsm) and the urinary albumin/creatinine and NAG/creatinine ratios. The data collected corresponded to two moments, when VUR was diagnosed and when it had already disappeared. Results: Quantitative differences were verified in the three functional parameters when comparing those corresponding to both moments of the study. In the qualitative analysis, in relation to the intensity of the VUR, differences were observed in UOsm at diagnosis and in the albumin/creatinine ratio once the VUR had cured. At this last moment, a significant increase in the albumin/creatinine ratio was observed in patients with loss of renal parenchyma in relation to those without residual morphological lesions. (AU)

[Reflux nephropathy and scarring nephropathy: So close and yet so different]. / Nefropatía de reflujo y nefropatía cicatricial. Dos entidades tan cercanas pero funcionalmente tan distintas.

OBJECTIVES: Reflux nephropathy is a radiologic condition commonly used to express the existence of renal morphological lesions in patients who have or had vesicoureteral reflux (VUR). This morphological concept is used based on the image data collected, without conducting basic complementary renal function studies. The present study was designed to demonstrate that patients with active VUR present different functional renal alterations from those shown by patients with disappeared VUR. PATIENTS AND METHODS: Longitudinal descriptive retrospective analysis including 89 children (46M, 43F) with VUR diagnosis through a standard voiding cystourethrogram (VCUG). The basic renal function tests collected were the maximum urinary osmolality (UOsm) and the urinary albumin/creatinine and NAG/creatinine ratios. The data collected corresponded to two moments, when VUR was diagnosed and when it had already disappeared. RESULTS: Quantitative differences were verified in the three functional parameters when comparing those corresponding to both moments of the study. In the qualitative analysis, in relation to the intensity of the VUR, differences were observed in UOsm at diagnosis and in the albumin/creatinine ratio once the VUR had cured. At this last moment, a significant increase in the albumin/creatinine ratio was observed in patients with loss of renal parenchyma in relation to those without residual morphological lesions. CONCLUSIONS: Concentrating ability defect is the most frequent finding in children with active reflux (true reflux nephropathy), whereas the most frequent functional disturbance found, once VUR has cured, is an increase in urinary albumin excretion, related to parenchymal damage. The term dysplastic-scarring nephropathy, could be more appropriate for patients with residual morphological lesions and impaired renal function, once VUR is cured.

[Determination of renal function at the end of the follow-up period in children with vesicoureteral reflux]. / Determinación de la función renal al final del periodo de seguimiento en niños diagnosticados de reflujo vesicoureteral.

OBJECTIVES: Vesicoureteral reflux (VUR) has been associated, since the old times, with chronic renal failure (CRF). Nevertheless, some functional parameters may be altered before glomerular filtration rate deteriorates, such as maximum urinary osmolality (Uosm) and urinary excretion of microalbumin. METHODS: We retrospectively studied the records of 77 children (37 males and 14 females; 48% and 52% respectively) with the diagnosis of VUR that were cured at the time of the study and were two years old or older (6.28 +/- 3.75; range: 2-16 years). In addition to Uosm and urinary excretion of microalbumin, the grade of VUR, creatinine levels, GFR, and morphological anomalies detected in 99Tc dimercaptosuccinate gammagrams (DMSA) were collected. RESULTS: Only four patients had moderate CREF. No differences in Uosm values were observed according to VUR grade. All children with grade I and II VUR had a normal renal concentration test. A long-term concentration defect was observed in 15 children, six with grade III, 8 with grade IV and 1 with grade V. Only 2 patients with normal DMSA had reduced Uosm. Uosm had a direct correlation with GFR (r = 0.6; p < 0.001). Regarding urinary excretion of microalbumin, elevated values were found in 11 children, one with grade II, four with grade III, and six with grade IV. Only four patients with normal DMSA showed microalbumin values over the normal range. A negative correlation between osmolality levels and microalbumin/creatinine quotient was observed (r = - 0.37; p < 0.001). In comparison with patients with normal DMSA, patients with bilateral scars showed significantly lower values of Uosm and GFR. CONCLUSIONS: At the end of the follow-up period we observed a defect on concentration capacity in 19.5% and increase of microalbuminuria in 14.3% of the children with the diagnosis of VUR. The frequency of CRF in our series is very low (5.1%). The observed renal tubular function deterioration is more in relation with the loss of renal parenchyma than the initial grade of VUR.

Determinación de la función renal al final del periodo de seguimiento en niños diagnosticados de reflujo vesicoureteral / Determination of renal function at the end of the follow-up period in children with vesicoureteral reflux

Objetivo: El reflujo vesicoureteral (RVU) se ha asociado, desde antiguo, a insuficiencia renal crónica (IRC). No obstante, antes de alterarse el filtrado glomerular, pueden afectarse algunos parámetros funcionales como la osmolalidad urinaria máxima (Uosm) y la eliminación urinaria de microalbúmina. Métodos: Se han estudiado retrospectivamente las historias clínicas de 77 niños (37 varones y 40 mujeres; 48% y 52%, respectivamente) diagnosticados de RVU y que en el momento del estudio estaban curados y tenían dos o más años de edad (6.28±3.75: rango: 2-16 años). Además de la Uosm y la eliminación urinaria de microalbúmina, se recogieron el grado de RVU, los niveles de creatinina y GFR y las anomalías morfológicas detectadas en las gammagrafías realizadas con ácido Tc-99 dimercaptosuccínico (DMSA). Resultados: Sólo cuatro pacientes tenían IRC moderada. No se observaron diferencias en los valores de Uosm según los grados de RVU. Todos los niños con RVU de grado I y II tuvieron una prueba de concentración renal normal. Se observó defecto de concentración a largo plazo en 15 niños, seis con grado III, ocho con grado IV y uno con grado V. Sólo dos pacientes con DMSA normal tuvieron la Uosm reducida. La Uosm se correlacionó directamente con el GFR (r = 0.6; p< 0.001). Con respecto a la eliminación urinaria de microalbúmina, se comprobaron valores elevados en 11 niños, uno con grado II, cuatro con grado III y seis con grado IV. Únicamente, cuatro pacientes con DMSA normal mostraron valores de microalbúminuria por encima de lo normal. Se observó una correlación negativa entre los niveles de osmolalidad y el cociente microalbúmina/creatinina (r = -0.37; p< 0.001). Los pacientes con cicatrices bilaterales mostraron con respecto a aquellos con DMSA normal, valores significativamente reducidos de Uosm y de GFR. Conclusiones: Al final del periodo de seguimiento, hemos comprobado defecto de la capacidad de concentración en el 19.5% y aumento de la microalbuminuria en el 14.3% de los niños que habían sido diagnosticados de RVU. La frecuencia de IRC en nuestra serie es muy reducida (5,1%). El deterioro observado de la función renal se relaciona con la pérdida de parénquima renal más que con el grado inicial de RVU (AU)

Objectives: Vesicoureteral reflux (VUR) has been associated, since the old times, with chronic renal failure (CRF). Nevertheless, some functional parameters may be altered before glomerular filtration rate deteriorates, such as maximum urinary osmolality (Uosm) and urinary excretion of microalbumin. Methods: We retrospectively studied the records of 77 children (37 males and 14 females; 48% and 52% respectively) with the diagnosis of VUR that were cured at the time of the study and were two years old or older (6.28 ± 3.75; range: 2-16 years). In addition to Uosm and urinary excretion of microalbumin, the grade of VUR, creatinine levels, GFR, and morphological anomalies detected in 99Tc dimercaptosuccinate gammagrams (DMSA) were collected. Results: Only four patients had moderate CRF. No differences in Uosm values were observed according to VUR grade. All children with grade I and II VUR had a normal renal concentration test. A long-term concentration defect was observed in 15 children, six with grade III, 8 with grade IV, and 1 with grade V. Only 2 patients with normal DMSA had reduced Uosm. Uosm had a direct correlation with GFR (r = 0.6; p < 0.001). Regarding urinary excretion of microalbumin, elevated values were found in 11 children, one with grade II, four with grade III, and six with grade IV. Only four patients with normal DMSA showed microalbumin values over the normal range. A negative correlation between osmolality levels and microalbumin/creatinine quotient was observed (r = - 0.37; p < 0.001). In comparison with patients with normal DMSA, patients with bilateral scars showed significantly lower values of Uosm and GFR. Conclusions: At the end of the follow-up period we observed a defect on concentration capacity in 19.5% and increase of microalbuminuria in 14.3% of the children with the diagnosis of VUR. The frequency of CRF in our series is very low (5.1%). The observed renal tubular function deterioration is more in relation with the loss of renal parenchyma than the initial grade of VUR (AU)

Válvulas de uretra posterior y ausencia de reflujo vesicoureteral bilateral: Seguimiento de la función renal / Posterior urethral valves and lack of bilateral vesicoureteral reflux: Renal function follow-up background

Introducción. Las válvulas de uretra posterior congénitas son repliegues de mucosa que se originan únicamente en varones. Constituyen la causa más común de obstrucción de la vía urinaria en el período neonatal. Debido a la alta presión que se genera en la vejiga urinaria, con frecuencia se acompañan de reflujo vesicoureteral (RVU) bilateral. En ocasiones, el reflujo es unilateral, asociado a displasia renal homolateral (síndrome VURD). Se ha comunicado que en estos casos el pronóstico a largo plazo es mejor, no obstante, existe muy poca experiencia sobre éste en el subtipo constituido por los niños en los que no existe reflujo. Métodos. Se estudiaron a 4 pacientes con válvulas de uretra posterior y ausencia de RVU, en seguimiento por un tiempo comprendido entre 3 y 6 años. Se describe su evolución desde el diagnóstico, la cirugía realizada, los marcadores de función renal, estudios de imagen y evolución. Así como los valores de los cocientes calculados entre las concentraciones urinarias de N-acetil-glucosaminidasa (NAG) y de microalbúmina con respecto a la creatinina urinaria. Resultados. La función glomerular renal fue normal en los 4 casos. Únicamente un paciente tenía un discreto defecto de la capacidad de concentración y un ligero incremento en la eliminación urinaria de NAG. Conclusiones. El manejo médico y quirúrgico de las válvulas de uretra posterior ha mejorado la supervivencia de los niños con este diagnóstico. La ausencia de RVU, la presencia de ascitis urinaria o urinoma en el período neonatal y la asociación con un gran divertículo vesical proveen un mecanismo de "escape", lo que resulta en una preservación de la función renal.

Introduction. The posterior urethral congenital valves are mucosal folds in the posterior urethra that occur only in male patients. They are the most common cause of urinary tract obstruction in the neonatal period. Due to hyper pressure that begins in the urinary bladder, it is highly frequent for these to come together with bilateral vesico-ureteral reflux. In some cases, this reflux is unilateral and is associated with posterior urethral valve and renal dysplasia (VURD syndrome). A better long-term renal outcome in these cases has been reported. Nevertheless, there is very little experience regarding prognosis of the remaining group of children without reflux. Methods. We studied 4 children with posterior urethral valves and lack of vesico-ureteral reflux with controlled follow-up during 3 and 6 years. We described disease presentation and clinical course from diagnosis, surgical intervention, renal function, radiologic features, N-acetylglucosaminidase (NAG), and microalbuminuria during follow-up. Results. Renal glomerular function is normal in all 4 cases. Only one patient had a mild default in urinary concentration capacity and a slight increase in urinary elimination of N-acetylglucosaminidase. Conclusion. Medical and surgical management of the posterior urethral valves has improved long-term renal outcome in the sepatients. Lack of vesico-ureteral reflux, urinary ascites, urinary extravasation, and large congenital bladder diverticula can serve as a pop-off mechanism to buffer hyperpressure in the urinary tract, leading to the preservation of improved renal function in boys with posterior urethral valves.