Glycosaminoglycan (GAG), Urine

Specimen requirement Spot urine (passed between 0900 and 1800 Hr)

Plain urine bottle

Volume: 20 mL
Authorisation code required No
24 Hr available service No
Method Spectrophotometry

Reference interval

Age specific reference interval:

Age

Urine Glycosaminoglycans (g/mol Cr)

0 – 5 months

< 52.0

6 – 12 months

< 31.5

1 – 1.9 years

< 29.9

2 – 3.9 years

< 21.3

4 – 5.9 years

< 14.4
6 – 7.9 years < 12.9
8 – 9.9 years < 11.6
10 – 14.9 years < 10.6
15 – 19.9 years < 6.7

≥ 20 years

 < 5.1

 

(Source: adapted from de Jong J G N et al. Clin Chem 1992; 38: 803 - 807)

Clinical indication

Screening for mucopolysaccharidoses (MPS)

Result interpretation

The mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by inherited deficiency of enzymes catalysing the stepwise degradation of glycosaminoglycans (GAGs). Increased excretion of GAGs in urine occurs. Clinical features are variable in different types of MPS and may include corneal clouding, organomegaly, skeletal abnormalities, and mental retardation.

 

Connective tissue, cartilage, liver, and lungs are rich in GAGs.

 

Very concentrated or very diluted urine samples may have GAGs inadequately isolated.

 

This assay may have false negative for MPS Type III and IV. For clinical suspicion of MPS Type III or IV and normal GAG result, please request urine GAG pattern analysis.

Heparin may give falsely high GAG result. This assay is interfered by albumin, haemoglobin and bilirubin. Please correlate with the drug history and interpret result with caution.
Measurement of uncertainty See table.
Frequency of measurement Monthly