Persistent asymptomatic proteinuria in children. Functional and ultrastructural evaluation with special reference to glomerular basement membrane (GBM) thickness.

Abstract

Seventeen children with persistent asymptomatic proteinuria were submitted to renal biopsy and to studies of renal function. The patients were re-evaluated 3 and 6 years later. The results of initial and follow-up functional studies were found to be normal despite persistent proteinuria. Findings on light microscopy of renal tissue samples were considered normal, and immunofluorescence microscopy revealed no deposition of immunoproteins or fibrinogen/fibrin. Electron microscopic surveys of nine patients demonstrated mild focal nonspecific changes of glomerular cells, and quantitative estimation of the widths of the GBM’s indicated statistically significantly increased thicknesses in all nine children. The limited number of observations seems to further emphasize the possibility that these patients may constitute a well-defined clinical entity, characterized by normal light and fluorescence microscopy with slight but significant thickening of the GBM.