[Study of renal function in infants diagnosed with renal pyelectasis in the first year of life]

To evaluate glomerular and tubular function in a group of infants diagnosed with pyelectasis.

We studied 14 patients diagnosed with renal pelvis dilatation in-utero or during the first year of life. Creatinine concentrations, urinary excretion of calcium, citrate, oxalate, N-acetyl-D-glucosaminidase (NAG), microalbumin and maximum urine osmolality after administration of intranasal desmopressin were determined. The latter three variables were determined at diagnosis and at the end of follow-up.

In all patients creatinine levels were normal. In six patients (42.9%) maximum urine osmolality values were abnormal. In four patients NAG/creatinine concentrations were elevated and in another four patients (28.6%) albumin urinary excretion was elevated. These anomalies tended to return to normal but, at the end of the study, three patients (21.4%) showed increased albuminuria and one (7.1%) showed persistently defective renal concentrating capacity. Ten patients showed metabolic urinary anomalies, potentially leading to the formation of stones (isolated hypercalciuria in five [35,7%], hyperoxaluria in two and hypocitraturia in one, and hypercalciuria associated with hyperoxaluria in two).

All patients showed normal glomerular function. Some patients presented increased albuminuria and moderate tubular function abnormalities, both of which tended to return to normal. Although studies with greater numbers of patients are needed, we propose that pyelectasis maybe a predictor of risk for lithiasis at later stages of life.