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Test Code U MPS QNT MPS Quantitation, Urine

Clinical System Name

Mucopolysaccharides Quant, Urine

Synonyms

GAG

Glycosaminoglycans

Acid Mucopolysaccharides

Description

Quantitative DMB dye binding test used to screen individuals suspected of having a mucopolysaccharidosis.

 

Sample Requirements

Specimen: Urine

Container(s): Sterile Screw-Capped Container/Tube

Preferred Vol:  2.0 mL

Minimum Vol: 1.0 mL

 

Note:   24 hour urine samples are acceptable, but not preferred.

Processing Instructions

Reject due to:

Spin:Y (samples received frozen do not need to be thawed and spun in CPA)

Aliquot:Y

Temp:-20 C

Storage location: BCG Box

 

Off-site collection:  Ship frozen.

Stability

Temperature Time
Room temp ≤24 hrs
Refrigerated  2 d
Frozen  3 wks

 

Availability

STAT Performed TAT
N Twice weekly 7 days

 

Contact the Biochemical Genetics Lab for requests outside of stated availability (206)987-2216.

Performing Laboratory

Seattle Children's Laboratory    

Department

Department:  Biochemical Genetics

Phone Number: 206-987-2216

 

 

Methodology

Method: Dimethylene Blue (DMB) Spectrophotometric Assay

Analytical Volume:

Limitations: Elevated protein and bilirubin in urine can cause false elevation.

CPT Codes

83864

Requisition

Biochemical Genetics Requisition

 

On the requisition include clinical information needed for appropriate interpretation. (Age, gender, diet (e.g. TPN therapy), drug therapy and family history)

Clinical Utility

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 as well as mg/L. Both are typically elevated in patients with storage disease, however, patients with Morquio have been known to have normal excretion. In patients who have had bone marrow transplant, CSF may be assayed to assess the efficacy of the treatment on the central nervous system.

Reference Ranges

Age mg/G Creat mg/L

0 - 2 mo

< 350 < 60
3 - 6 mo < 250 < 60
7 - 18 mo < 150 < 60
19-24 mo <125 < 60
> 2 yr < 60 < 60