[Enzymuria and kidney diseases in childhood].

Urinary enzyme excretion and proteinuria were studied in 316 children with different underlying diseases. Activities on N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase decreased progressively with age in the urine of 66 healthy prematures, newborns, infants or children. In 51 children with nephrotic syndrome, tubulopathies or chronic renal failure, excretion of NAG and AAP rose 3 to 30 fold. Contrary to molecular weight dependent protein analysis, determination of enzymuria did not allow to differentiate between glomerular and tubular disorders. After renal transplantation, 31 out of 52 children had a pathological enzymuria. NAG and AAP were more frequently elevated during treatment with cyclosporine A (21/29), than with azathioprine (10/23). The influence of nephrotoxic drugs upon enzymuria was documented in 14 children with cystic fibrosis or septicaemia treated with tobramycin. Activities of NAG and AAP rose transiently, whereas proteinuria remained almost unchanged. Only three out of 45 children receiving nonsteroidal antiinflammatory drug therapy for juvenile rheumatoid arthritis or spondylarthritis showed a pathological increase in enzymuria. Mean urinary NAG and AAP excretion in 154 children with insulin dependent diabetes mellitus were not different from controls and were unrelated to either duration of disease or HbA1 concentration. The determinations of urinary enzymes as non-invasive tests of renal integrity in medicine and toxicology provide a very sensitive indicator of renal damage. The assays of NAG and AAP have proven to be most valuable; however, due to a lack of specificity for the type and origin of renal dysfunction, these urinary enzyme assays are most useful when carried out in conjunction with electrophoretic analyses of proteinuria.