Tubular functions in glomerulonephropathies in childhood

Assessment of tubular functions by mean of concentration, urinary sodium excretion and urinary acidification following a short ammonium-chloride-loading test were studied in 18 minimal-change nephrotics (MC-NS), in 12 nephrotics associated with focal segmental glomerulosclerosis (FSG), in 5 nephrotics associated with membranoproliferative glomerulonephritis (MPGN) and in 10 patients with lupus nephritis. Normal tubular functions in respect to maximal urinary concentration (U/P osmolar ratio greater than 2.5), value of FENa of less than 1.0, and maximal urinary acidification were observed in the MC-NS group. In contrast, defects in maximal urinary concentration and urinary acidification were documented in the nephrotics associated with FSG and MPGN. Submaximal urinary acidification was also noted in lupus nephritis. The mean value of FENa were also higher than 1.0 in MPGN and lupus nephritis.