Renal Parenchymal Area and Risk of ESRD in Boys with Posterior Urethral Valves

Abstract

Background and objectives Approximately 20% of boys with posterior urethral valves develop ESRD; however, few factors associated with the risk of ESRD have been identified. The objective of this study was to determine if renal parenchymal area, defined as the area of the kidney minus the area of the pelvicaliceal system on first postnatal ultrasound, is associated with the risk of ESRD in infants with posterior urethral valves.Design, setting, participants, & measurements A retrospective cohort of boys who were diagnosed with posterior urethral valves at less than 6 months of age between 1988 and 2011 and followed for at least 1 year at a freestanding children's hospital was assembled. Cox proportional hazard regression and Kaplan-Meier analysis were used to estimate the association between renal parenchymal area and time to ESRD. Cox models were adjusted for age at presentation, minimum creatinine 1 month after bladder decompression, and vesicoureteral reflux.Results Sixty patients were followed for 393 person-years. Eight patients developed ESRD. Median renal parenchymal area was 15.9 cm 2 (interquartile range=13.0-21.6 cm 2 ). Each 1-cm 2 increase in renal parenchymal area was associated with a lower risk of ESRD (hazard ratio, 0.64; 95% confidence interval, 0.42 to 0.98). The rate of time to ESRD was 10 times higher in boys with renal parenchymal area,12.4 cm 2 than boys with renal parenchymal area$12.4 cm 2 (P,0.001). Renal parenchymal area could best discriminate children at risk for ESRD when the minimum creatinine in the first 1 month after bladder decompression was between 0.8 and 1.1 mg/dl. ConclusionIn boys with posterior urethral valves presenting during the first 6 months of life, lower renal parenchymal area is associated with an increased risk of ESRD during childhood. The predictive ability of renal parenchymal area, which is available at time of diagnosis, should be validated in a larger, prospectively-enrolled cohort.

Congenital Urinary Tract Obstruction: The Long View

“…2 Careful measurement of renal parenchymal area has been shown to reliably predict kidney failure in these patients. 50 We have recently reported that in murine models of polycystic kidney disease, enlarging cyst size is tightly correlated with obstruction of cystic as well as adjacent noncystic nephrons, which undergo cellular destruction and formation of atubular glomeruli similar to the process following UUO. 51 Thus, polycystic kidney disease appears to be a form of obstructive nephropathy, with obstruction at the level of collecting ducts rather than the ureter.…”

The Fate of Nephrons in Congenital Obstructive Nephropathy: Adult Recovery is Limited by Nephron Number Despite Early Release of Obstruction

“…This has been borne out in male infants under 6 months of age with lower urinary tract obstruction: lower renal parenchymal area is associated with increased risk of renal failure later in life. 28 To complement the measurement of renal parenchymal area, a promising new technique is being developed to measure the number and size of glomeruli using magnetic resonance imaging in whole human kidneys labeled with cationic ferritin. 29 …”

Renal development in the fetus and premature infant

“…Various measures have been attempted to predict long term outcomes of fetal hydronephrosis. Serum creatinine at one year of life seems to be the best predictor of long term outcomes [158,159], although recently ultrasound assessment of renal parenchymal area has been proposed as a marker [160]. …”