Urinary glycosaminoglycan (uGAG) excretion in healthy pediatric and adolescent population

The influence of age and gender factor on the urinary excretion of total glycosaminoglycans (uGAGs) and their particular types: chondroitin/dermatan sulfates (CS/DSs), heparan sulfates (HSs) and hyaluronan (HA) was analyzed in healthy pediatric and adolescent population.

Urine samples were collected from 95 healthy children. Sulfated GAGs excreted in the urine were quantitated using standardized dye-binding method, while the concentrations of HA were determined by immunoassay.

Age-dependent decline in total uGAG excretion (r=-0.686; p<0.001), resulting from a decrease in particular GAG fractions i.e. CS/DS (r=-0.757; p<0.001), HS (r=-0.401; p<0.05) and HA (r=-0.638; p<0.001), was found in healthy subjects. The observed differences were not gender specific with the exception of HS, in which excretion declines with age in males (r=-0.501; p<0.05) and does not change in females. Changes in the distribution pattern of uGAG were also found. CS/DS were the predominant uGAG's fraction, representing from 55% to 76% of the total GAGs. Children up to 3 years excreted more GAGs than older subjects and with a higher proportion of CS/DS and less content of HS. Moreover, the relative contribution of HA was increased twofold in adolescents, aged 15-18, as compared to younger subjects. A negative correlation existed between uGAG excretion and body height, except for HS, for which this relationship was found only in males.

Changes in urinary distribution pattern of particular GAG types during physiological human growth and development were found. Evaluation of urinary GAG screening procedures during pathological conditions should be based on the GAG/creatinine ratios with age and gender taken into account.