Overall and single-kidney clearance in children with urinary tract infection and damaged kidneys

The overall and single-kidney clearance in children with acute urinary trac t infection was investigated retrospectively using the combination of the r elative Tc-99m-dimercaptosuccinic acid (DMSA) uptake and the Cr-51-ethylene diaminetetraacetic acid clearance. Methods: There were 180 patients with bo th normal kidneys, 56 with clear unilateral abnormalities an DMSA scintigra phy and 11 with two abnormal kidneys. Half of the patients were younger tha n 2 y, and because of the progressive maturation of the renal function, the y were not considered in the analysis of the absolute overall and single-ki dney clearance; nevertheless, they were included in the analysis of the rel ative DMSA percentage uptake. Results: When only one kidney was affected on DMSA scintigraphy, the clearance of the affected kidney was lower than on the normal side and often abnormally low. In these unilaterally affected ki dneys, contralateral compensation mechanisms tended to occur, resulting in preservation of overall clearance. This compensation was probably not prese nt only on the contralateral side. On the abnormal side, the clearance was normal in about half of the cases, probably because of intrarenal compensat ion occurring in regions not damaged by the infection. in addition to these compensation mechanisms, hyperfiltration was probably present in many case s of acute urinary tract infection with intact or unilaterally damaged kidn eys.