Lab Test

Arylsulfatase A, Urine

ARSA Deficiency

Test Codes

MAYO: ARSU, EPIC: LAB5947, SOFT: XARSA

Instructions

Please refer to the Specimen Collection Manual for instructions on 24 Hour Urine Collection:

Specimen Collection Criteria

Collect: 24 hour urine sample with no preservative.

  • Critical refrigerated. 24 hour urine specimen MUST be kept on ice or refrigerated throughout collection and transport.
  • Include start and end dates and times for the collection period on the specimen container.
Urine Preservative Options
No Preservative
6N Hydrochloric Acid
Boric Acid (10g)
Sodium Carbonate
50% Acetic Acid
REQUIRED
Unacceptable
Unacceptable
Unacceptable
Unacceptable

Physician Office/Draw Specimen Preparation

Maintain specimens refrigerated (2-8°C or 36-46°F) prior to transport.

Preparation for Courier Transport

Transport: Entire 24 hour urine collection, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

Specimens not collected and processed as indicated. 

In-Lab Processing

Measure total volume of 24 hour urine specimen. Record total volume and collection start and end dates and times in the LIS system. Aliquot 6.0 mL from the well-mixed 24 hour urine collection. (Minimum: 2.5 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Sendout Laboratory with any questions.

Laboratory

Sent to Mayo Medical Laboratory, Rochester, MN.

Performed

Varies.
Results available within 10-17 days.

Reference Range

Greater than 19 nmol/h/mL.

Test Methodology

Colorimetric, Enzyme Assay.

Interpretation

Arylsulfatase A is a lysosomal enzyme which exhibits markedly decrease activity in patients with metachromatic leukodystrophy, an inherited metabolic disorder. This results in the accumulation of galactosyl sulfatides in the CNS, peripheral nerves, and organs.

Clinical Utility

Determination of arylsulfatase A in the urine can be used as a screening test for metachromatic leukodystrophy since affected patients contain decreased urinary arylsulfatase A activity.

Clinical Disease

Metachromatic leukodystrophy (MLD) is an autosomal recessive demyelinating disorder caused by deficiency of arylsulfatase A, an enzyme responsible for degradation of cerebroside sulfate, a major constituent of myelin lipids. Neurologic signs include ataxia, optic atrophy, mental deterioration, spasticity, and coma, though age of onset can vary from infancy to adulthood, correlating to some degree with amount of residual enzyme activity. A variety of mutations are characterized in the gene, allowing for molecular diagnosis to supplement nerve conduction studies, sural nerve biopsy, and enzymatic assays.

CPT Codes

84311

Contacts

Last Updated

4/10/2021

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