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Age-related concentrations of glycosaminoglycans in random urine: A contribution to the laboratorial detection of mucopolysaccharidoses

Roberto Giugliani^I,II; Carlos Severo Dutra-Filho^I,III; Maria Luiza Barth^I; Valquiria Enk^I; Carlos Alexandre Netto^III

^IUnidade de Genética Médica, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos, 2350, 90210 Porto Alegre, RS, Brasil. Send correspondence to R.G.
^IIDepartamento de Genética, Universidade Federal do Rio Grande do Sul, 90210 Porto Alegre, RS, Brasil
^IIIDepartamento de Bioquímica, Universidade Federal do Rio Grande do Sul, 90210 Porto Alegre, RS, Brasil

ABSTRACT

The mucopolisaccharidoses (MPS) are routinely detected by the assay of urinary glycosaminoglycans (GAG), usually performed in 24-hour urine specimens. As suspect patients are generally children without micturition control and as GAG excretion values vary with age, we studied random urine samples from 78 normal children and from 16 MPS patients 6 months to 12 years old, in order to (a) establish age-related normal values for the GAG/volume (GAG/L) and GAG/creatinine (GAG/CREAT) urinary ratios, and to (b) test the usefulness of these ratios in the identification of MPS patients.In both ratios GAG concentrations decrease with age. GAG/L and GAG/CREAT ratios discriminate all MPS patients, with one exception in each ratio, from normal patients. Our results indicate that random urine sasmples are suitable for GAG assay since patient's age is considered. It seems advisable to consider both the GAG/L and the GAG/CREAT ratios in the interpretation of the results, especially in young children.

Keywords: Glycosaminoglycans; Mucopolysaccharidoses.

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