Renal functional outcome in unilateral hydronephrosis in newborn pigs

Purpose: We followed the course of neonatally induced, partial unilateral u reteral obstruction in pigs and established whether early function or morph ological evaluation of the hydronephrotic kidney is predictive of outcome. Materials and Methods: In 25 piglets unilateral partial ureteropelvic obstr uction was induced 2 days after birth, while 11 underwent sham operation. O nly obstructed kidneys with significant dilatation at 4 weeks were included for further study. Renal function was assessed on renography using (99m)te chnetium-diaminetriaminepentaacetic acid differential uptake. According to the plasma clearance of (99m)technetium-diaminetriaminepentaacetic acid the glomerular filtration rate was determined at ages 4, 12 and 24 weeks. Kidn ey morphology was studied in parallel by magnetic resonance imaging. Results: A total of 12 obstructed kidneys with grade 3 or 4 hydronephrosis fulfilled study inclusion criteria. Of 6 kidneys with a functional share of 40% or greater at age 4 weeks 2 deteriorated to less than 40% at 24 weeks, while 4 of 6 with st share of less than 40% at age 4 weeks improved to gre ater than 40% at 24 weeks. The single kidney glomerular filtration rate at 4 weeks did not correlate with that at 12 or 24 weeks but the rate at 12 we eks correlated with that at 24 weeks (r(2) = 0.8140, p <0.001). Neither rel ative volume of the obstructed kidney nor length of the contralateral nonob structed kidney correlated with functional share of the obstructed kidney a t any age. Conclusions: Early evaluation of kidney function or volume, or contralatera l kidney length did not predict the outcome of neonatally induced unilatera l hydronephrosis in pigs.