Pediatric reference data on activity of urinary N-acetyl-β-D-hexosaminidase and its isoenzymes

Purpose: The objective of the study was to establish age - dependent values of the urinary lysosomal exoglycosidases activities: N-acetyl-β-D-hexosaminidase (HEX) and its isoenzyme A (HEX A) as well as isoenzyme B (HEX B) in healthy children and adolescents.

Material and methods: The study was performed using a random sample of 203 healthy children and adolescents (girls=99, boys=104), aged six months to 17.9 years. The activities of HEX, HEX A and HEX B were determined by a colorimetric method. The activities of the urinary HEX and its isoenzymes were expressed in pKat/μg of creatinine (pKat/μg Cr).

Results: Median concentrations of urinary HEX, and its HEX A, HEX B isoenzymes in particular age groups were analyzed using ANOVA. Urinary HEX, HEX A and HEX B activities (pKat/μg Cr) were the highest in children below 3 years, in comparison to remaining age groups. There were statistically significant negative correlations between urinary HEX, HEX A as well as HEX B and age (r=-0.24, p<0.001 (HEX); r=-0.20, p<0.01 (HEX A); r=-0.26, p<0.001 (HEX B), respectively. We constructed the reference values for urinary activity of HEX, HEX A and HEX B (pKat/μg Cr) in centiles according to age, in three-year intervals.

Conclusions: Reported data present, for the first time, reference values for urinary activities of HEX and its isoenzymes HEX A and HEX B in children and adolescent.