Renal function during hydropenia and water diuresis in children with recurrent urinary tract infections

SUMMARY The glomerular filtration rate (GFR), urinary concentrating and diluting capacity and sodium excretion have been determined in 17 children with previous histories of urinary tract infection confirmed by urine cultures. There were no signs or symptoms of infection at the time of the study. Renal function was found to be normal in patients with normal intravenous pyelographies (IVPs). In the patients with renal parenchymal changes a wide variety of functional changes could be found. Reduction of the glomerular filtration rate was the predominant lesion. The GFR could however not be predicted by the IVP-appearance. Most of the patients were able to increase the GFR during water diuresis. The glomerular-tubular balance for sodium was reset in 3 of the patients as manifested by an increased CNa/CIn. The concentrating capacity was also reduced in those 3 patients, indicating an impairment of the sodium reabsorption in the loop of Henle. All the patients were able to dilute the urine normally during water diuresis, but 5 of the patients were unable to increase their diluting capacity during the transition from hydropenia to water diuresis. It is noteworthy that only those patients were unable to increase the GFR significantly during the transition from hydropenia to water diuresis.