[Microproteinuria and enzymuria in fever and pyelonephritis in childhood. A prospective study of 180 children].

In 180 children (87 children belonging to a control group, 68 with fever of non-renal origin, and 25 with pyelonephritis) albumin and immunoglobulin G (markers for glomerular dysfunction), alpha-1-microglobulin and beta-NAG (markers for proximal tubular dysfunction) and apolipoprotein A1 (marker of "postrenal' dysfunction) were measured in second-voided morning urine. In children with fever of non-renal origin, glomerular dysfunction was encountered in 8.8%, tubular dysfunction in 17.6% and mixed glomerular-tubular dysfunction in 14.7% of cases. Among children with pyelonephritis, 28% revealed glomerular dysfunction and 44% mixed glomerular-tubular dysfunction. No case of solitary proximal tubular dysfunction was observed in children with pyelonephritis. There were highly significant differences in presence and expression of glomerular dysfunction between children with fever of non-renal origin and children with pyelonephritis (P < 0.0001), whereas with regard to proximal tubular dysfunction, the differences were only moderately significant (beta-NAG: P < 0.01) or of low significance (alpha-1-microglobulin: P < 0.05). This may indicate that morphologic changes occur during interstitial pyelonephritis due to inflammation of glomeruli, resulting in glomerular dysfunction, while proximal tubular dysfunction may additionally be due to fever-associated function processes.