Purpose: We determined the level of functional damage to the kidney which inhibits further growth.
Materials and methods: Renal functional volume and percent uptake of 34 kidneys with reflux were studied by performing sequential quantitative single photon emission computerized tomography 2 times at a mean interval of 3.2 years.
Results: Change in volume between the initial and repeat studies was 27.2 +/- 28.4% in all 34 kidneys. Change in volume was less than 7% in 8 kidneys and greater than 14% in 26. Receiver operating characteristic curve analysis indicated that 15.6% kidney uptake was associated with 75% sensitivity, 100% specificity and 94% accuracy in distinguishing kidneys with more than 7% from those with less than 7% change in volume. The value of kidney uptake of less than 15.6% was 100% in predicting less than 7% change in volume (positive predictive value) and the value of kidney uptake greater than 15.6% was 93% in predicting more than 7% change in volume (negative predictive value).
Conclusions: Kidney uptake of less than 15.6% represents irreversible impairment of renal growth and indicates permanent damage in kidneys with vesicoureteral reflux.