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Long-term followup of renal morphology and function in children with recurrent pyelonephritis
1Department of Pediatrics, Karolinska Institute, Huddinge Hospital, Sweden.
Insights
Recurrent pyelonephritis in children often leads to reduced kidney size and impaired kidney function, particularly in those with early-onset disease. Regular monitoring of glomerular filtration rate is crucial for managing this condition.
Area of Science:
- Pediatric Nephrology
- Urology
- Medical Imaging
Background:
- Recurrent pyelonephritis is a significant concern in children, potentially leading to renal damage.
- Vesicoureteral reflux and renal scarring are known complications that can affect kidney health.
Purpose of the Study:
- To evaluate renal morphology and function in children with recurrent pyelonephritis.
- To determine the long-term impact of pyelonephritis, vesicoureteral reflux, and renal scarring on kidney function.
Main Methods:
- Longitudinal study of 161 children with recurrent pyelonephritis over 1 to 21 years.
- Assessment of renal function using glomerular filtration rate and effective renal plasma flow.
- Evaluation of renal morphology, including scarring and kidney size.
Main Results:
- Reduced glomerular filtration rate (< -2 SD) was observed in 51-53% of patients, often associated with small or scarred kidneys.
- Kidney size, not vesicoureteral reflux grade, was the primary determinant of reduced glomerular filtration rate.
- Bilateral small kidneys and surgery for high-grade reflux correlated with greater functional decline.
Conclusions:
- Renal functional damage in recurrent pyelonephritis often occurs early and is linked to kidney size.
- Slow progression of renal dysfunction is observed, but difficult to predict from imaging alone.
- Regular glomerular filtration rate monitoring is essential for managing children with recurrent pyelonephritis.
Abstract:
Renal morphology and function were evaluated in 161 children with recurrent pyelonephritis with or without vesicoureteral reflux and with or without scarred or small kidneys. The patients were followed for 1 to 21 years. Renal function was determined by glomerular filtration rate and effective renal plasma flow by clearances of inulin and paraaminohippuric acid. Of 105 children with normal kidneys originally small or scarred kidneys developed in 37, of whom 22 had grade III or greater vesicoureteral reflux, while small kidneys developed in 13 of 29 children with renal scarring originally. Of the 37 children with normal kidneys originally renal parenchymal scarring developed in 14 after the age of 4 to 5 years. Glomerular filtration rate was already < -2 standard deviations of that of controls in 51% of the patients at the first and in 53% at the last investigation of renal function. Of these patients with a glomerular filtration rate of < -2 standard deviations 69% had small or parenchymally reduced kidneys most of whom had the first pyelonephritis episode before age 3 years. Patients with small kidneys had a lower glomerular filtration rate than those with normal sized kidneys, whether scarred or not. The low glomerular filtration rate and its subsequent further reduction were related to kidney size and not to the presence or degree of vesicoureteral reflux. However, in individual patients the rate of functional deterioration could not be predicted from the radiological findings. Patients with bilateral small kidneys seemed to show the greatest decrease in glomerular filtration rate during followup as did those with grade III or greater reflux undergoing surgery bilaterally and those patients also had a lower glomerular filtration rate at the last investigation compared to patients not undergoing surgery. In conclusion, renal functional damage seems to occur early in the course of the disease and seems to be related to kidney size but there is a further slow progression with reduction in renal function which occurs, although this is difficult to predict from the radiological changes in individual patients. Therefore, patients with recurrent pyelonephritis should be followed regularly by glomerular filtration rate determination using an accurate method.