Pathology Handbook

Glycosaminoglycans (GAGS)

Synonyms

GAGS, mucopolysaccharides

Clinical Indications

  • Hepatomegaly
  • Skeletal deformities
  • Abnormal faces
  • Behavioural problems
  • Inguinal and umbilical hernias
  • Loss of developmental skills

Request Form 

Request on ICE

Availability

On request.

Specific Criteria

None

Turnaround Time

GAG quantification - 7 days
GAG typing - 21 days

Specimen

Urine in white-top universal

Volume

5.0 mL

Container

White-top universal

Urine bottle white top

Lab Handling

Sent to referral laboratory (Addenbrookes, Cambridge)

Collection

Samples should be transported to laboratory immediately.

Causes for Rejection

  • Unlabelled or incorrectly labelled sample
  • Not meeting specific criteria for analysis
  • Delay in sample reaching laboratory 
  • Sample in wrong sample container.

Interpretation

Please see the report.

Initially, samples are screened for total glycosaminoglycan concentration. False positive results are common, particularly in young infants. Positive results will be referred for typing by electrophoresis if clinical details suggestive of a mucopolysaccharidosis are given. False negative quantitative results may also be encountered, therefore if there is a strong clinical suspicion of a mucopolysaccharidosis, please specifically request GAG typing. If urine glycosaminoglycan typing and white cell enzymes are normal and a storage disorder is still suspected clinically, urinary oligosaccharide and sialic acid analysis should be considered.