The urinary activity of arylsulfatase A (ASA), a lysosomal enzyme of proximal kidney tubules, was evaluated in children aged 6 to 16 with with a diagnosis of urinary tract infection (UTI). All patients had normal glomerular filtration rates (GFR); they were divided into 2 groups: I-with UTI only, II-with UTI and anomalies of urinary tract. Similar measurements of ASA activity were obtained for a control group of healthy children - group III. The ASA activity was compared with N-acetyl-beta-D-glucosaminidase (NAG) activity and beta-2-microglobulin (B2M) concentrations in urine - these compounds being presumed markers of damage to proximal kidney tubules. An increased ASA activity was observed in both groups of studied patients with UTI. Those found in group II children were the highest and were statistically significantly elevated above controls. There was also a positive correlation between ASA activity and NAG activity in these children. The results indicate the usefullness of measuring urinary ASA activity as a marker of proximal kidney tubule damage in children with UTI and structural anomalies of the urinary tract. There is also the implication that children with UTI and these anomalies are more susceptible to damage to the proximal tubules.

Keywords: urinary ASA, urinary tract infection, damages of nephron proximal tubules, urinary NAG