[Microproteinuria as a marker of renal damage in children]

Elevated urinary levels of microproteinuria or renal enzyme have shown to be associated with renal injury. Data collected in children with vesico-ureteral reflux (VUR) or hydronephrosis have been evaluated to identify a means of predicting renal damage.

Levels of urinary microproteinuria (N-acetyl-beta-glucosaminidase, aminoalanina peptidase, lisozyme, beta(2)-microglobulin) were evaluated with immunoassay in catheterized or voided urine. The levels of urinary creatinine were also determined. Of the 85 children enrolled in this study 22 were affected from reflux, 16 had hydronephrosis. Urine was obtained from the bladder in all children and also from renal pelvis in 9 patients at surgery for ureteropelvic junction obstruction. In addition, urine was obtained from 27 patients with a variety of pathophysiological conditions (neoplasia, ematuria, parenteral nutrition, ecc.). Normal healthy controls were performed in 20 children who volunteered for the study.

In the group of children affected from reflux urinary microprotein elevated levels were in 18. In children with hydronephrosis pathological findings were observed in 2 cases. Abnormal pattern was found in 27 patients as response to various agents. Data obtained in healthy children were normal. Sensitivity in reflecting renal damage makes urinary enzymes measurement attractive as an indicator of renal dysfunction.

Urinary microproteinuria evaluation may be a useful marker of progression of renal injury in children with reflux. However, excretion level of these microproteins is not helpful in identifying upper tract obstruction in small children, but values arise in those left untreated.