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Diagnostic Services

Genetics Lab


Mucopolysaccharide (GAG) Quantitation

The mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by a deficiency of lysosomal enzymes catalyzing the degradation of glycosaminoglycans (GAG) (mucopolysaccharides). Depending on the enzyme deficiency, the catabolism of dermatan sulfate, heparan sulfate, keratan sulfate, chondroitin sulfate, or hyaluronan, may be blocked singly or in combination. Lysosomal accumulation of GAG molecules results in cell, tissue, and organ dysfunction. The MPSs share many clinical features, although in variable degrees. The disorders are chronic and progressive, and usually display a wide spectrum of clinical severity within one enzyme deficiency. GAG fragments generated by alternative pathways are excreted in urine, providing the basis for diagnostic screening for the MPS. Urine values are expressed as a GAG/creatinine ratio. In patients who have had bone marrow transplant, CSF may be assayed to assess the efficacy of the treatment on the central nervous system.

Test Name: Mucopolysaccharide Quantitative Urine
Test Code:
Test Description:
Quantitative measurement of total glycosaminoglycan excretion in the urine relative to the level of creatinine in the urine.
MPS, urinary GAGs, GAG
This test is used to screen individuals suspected of having a mucopolysaccharidosis.
Related Tests: Mucopolysaccharide electrophoresis  
This is a follow-up test to mucopolysaccharide quantitation, or urine metabolic screen that indicated the individual has elevated GAG excretion.

Clinical Links: National MPS Society
Performed twice weekly, not available STAT
Turnaround Time:
7 days
Spectrophotometric assay
Reference Range:
Interpretive report will be provided
Consent Form:
Sample Requirements: Type
Urine: 2 ml random urine
CSF: 1 ml CSF

Urine/CSF: Freeze in plastic aliquot

Ship frozen overnight.
Samples Received:
Mon - Fri 8:00am - 5:00 pm PST
Special Considerations:
Please e-mail Client Services or call at 206-987-2617 with any billing questions
CPT Code:
Please e-mail Client Services or call at 206-987-2617 with any billing questions