Test Catalog

Test Id : ARSU

Arylsulfatase A, 24 Hour, Urine

Useful For
Suggests clinical disorders or settings where the test may be helpful

Detection of arylsulfatase A deficiency using urine specimens

 

This test is not suitable for carrier detection.

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

Metachromatic leukodystrophy (MLD) is caused by deficient activity of arylsulfatase A (ARSA) enzyme and is characterized by progressive neurologic changes and leukodystrophy with variable age of onset.

 

Pseudodeficiency of arylsulfatase A (ARSA) enzyme has been recognized with increasing frequency among patients with other apparently unrelated neurologic conditions as well as among the general population.

 

This test is not suitable for carrier detection.

 

Leukocytes are the preferred screening specimen for metachromatic leukodystrophy.

 

Additional studies, such as molecular genetic testing of ARSA (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify ARSA Gene List ID: IEMCP-WHFH2K ), urinary excretion of sulfatides (CTSA / Ceramide Trihexosides and Sulfatides, Urine), and histological analysis for metachromatic lipid deposits in nervous system tissue are recommended to confirm a diagnosis.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Colorimetric, Enzyme Assay

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Arylsulfatase A, U

Aliases
Lists additional common names for a test, as an aid in searching

ARSA Deficiency

Arylsulfatase A Deficiency

Metachromatic Leukodystrophy

MLD

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Specimen Type
Describes the specimen type validated for testing

Urine

Ordering Guidance

The preferred test to rule-out metachromatic leukodystrophy is ARSAW / Arylsulfatase A, Leukocytes.

Shipping Instructions

Specimen must be received at least 1 day prior to assay day for processing.

Necessary Information

24-Hour volume is required.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL tube

Specimen Volume: 6 mL

Collection Instructions:

1. Collect a 24-hour urine specimen.

2. No preservative.

3. Refrigerate specimen during collection.

Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602)

3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.

Urine Preservative Collection Options

Note: The addition of preservative or application of temperature controls must occur within 4 hours of completion of the collection.

Ambient

No

Refrigerate

Required

Frozen

No

50% Acetic Acid

No

Boric Acid

No

Diazolidinyl Urea

No

6M Hydrochloric Acid

No

6M Nitric Acid

No

Sodium Carbonate

No

Thymol

No

Toluene

No

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

2.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 14 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Detection of arylsulfatase A deficiency using urine specimens

 

This test is not suitable for carrier detection.

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

Metachromatic leukodystrophy (MLD) is caused by deficient activity of arylsulfatase A (ARSA) enzyme and is characterized by progressive neurologic changes and leukodystrophy with variable age of onset.

 

Pseudodeficiency of arylsulfatase A (ARSA) enzyme has been recognized with increasing frequency among patients with other apparently unrelated neurologic conditions as well as among the general population.

 

This test is not suitable for carrier detection.

 

Leukocytes are the preferred screening specimen for metachromatic leukodystrophy.

 

Additional studies, such as molecular genetic testing of ARSA (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify ARSA Gene List ID: IEMCP-WHFH2K ), urinary excretion of sulfatides (CTSA / Ceramide Trihexosides and Sulfatides, Urine), and histological analysis for metachromatic lipid deposits in nervous system tissue are recommended to confirm a diagnosis.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Metachromatic leukodystrophy (MLD) is a lysosomal storage disorder caused by a deficiency of the arylsulfatase A (ARSA) enzyme, which leads to the accumulation of sulfatides (both galactosyl and lactosyl sulfatide) in the white matter of the central nervous system, the peripheral nervous system, and to a lesser extent, in visceral organs including the kidney and gallbladder. Cells that produce myelin are especially affected causing the characteristic leukodystrophy seen in MLD. Patients with MLD excrete excessive amounts of sulfatides in their urine.

 

The 3 clinical forms of MLD are late-infantile, juvenile, and adult, depending on age of onset. All forms result in progressive neurologic changes and leukodystrophy demonstrated on magnetic resonance imaging. Late-infantile MLD is the most common (50%-60% of cases) and usually presents before 30 months of age with hypotonia, clumsiness, diminished reflexes, and slurred speech. Progressive neurodegeneration occurs and, unless successfully treated, most patients do not survive past childhood. Juvenile MLD (20%-30% of cases) is characterized by onset between 30 months to 16 years. Presenting features are behavior problems, declining school performance, clumsiness, and slurred speech. Neurodegeneration occurs at a somewhat slower and more variable rate than the late-infantile form. Adult MLD (15%-20% of cases) has an onset after puberty and can be as late as the fourth or fifth decade. Presenting features are often behavior and personality changes, including psychiatric symptoms. Clumsiness, neurologic symptoms, and seizures are also common. The disease course has variable progression and may occur over 2 to 3 decades. The disease prevalence is estimated to be approximately 1 in 100,000.

 

MLD is an autosomal recessive disorder and is caused by variants in the ARSA gene coding for the ARSA enzyme. This disorder is distinct from conditions caused by deficiencies of arylsulfatase B (Maroteaux-Lamy disease) and arylsulfatase C (steroid sulfatase deficiency). Saposin B deficiency is a rare autosomal recessive disorder with symptoms that mimic MLD; however, the ARSA enzyme level is normal. Like MLD, patients with saposin B deficiency can also excrete excessive amounts of sulfatides in their urine. Individuals with multiple sulfatase deficiency, which is clinically distinct from MLD, will also have deficiency of arylsulfatase A, however, other sulfatase enzymes will also be deficient.

 

Individuals with "pseudodeficiency" of ARSA have very low levels of ARSA activity but are otherwise healthy. Pseudodeficiency is being recognized with increasing frequency among patients with other apparently unrelated neurologic conditions as well as among the general population, therefore a diagnosis of MLD cannot be based upon reduced ARSA activity alone To confirm a diagnosis, additional studies, such as molecular genetic testing of ARSA (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify Gene List ID: IEMCP-WHFH2K), urinary excretion of sulfatides (CTSA / Ceramide Trihexosides and Sulfatides, Urine), and/or histological analysis for metachromatic lipid deposits in nervous system tissue are recommended.

 

Current treatment options for MLD are focused on managing disease manifestations such as seizures, decline in mobility and cognitive ability, and feeding difficulties. Hematopoietic stem cell transplantation is an option but outcomes are dependent on the clinical stage and the presence of neurologic symptoms.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

> or =19 nmol/h/mL

Note: Results from this assay may not reflect carrier status because of individual variation of arylsulfatase A enzyme levels. Low normal values may be due to the presence of pseudodeficiency or carrier alleles. Patients with these depressed levels may be phenotypically normal.

Interpretation
Provides information to assist in interpretation of the test results

Reduced levels of arylsulfatase A are seen in patients with metachromatic leukodystrophy (MLD).

 

Individuals with pseudodeficiency of arylsulfatase A can have results in the affected range but are otherwise unaffected with MLD.

 

Abnormal results should be confirmed using CTSA / Ceramide Trihexosides and Sulfatides, Urine. If molecular confirmation is desired, consider molecular genetic testing of ARSA (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify Gene List ID: IEMCP-WHFH2K).

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Arylsulfatase A is also deficient in individuals with multiple sulfatase deficiency.

 

This test is not reliable in identifying carriers due both to analytical variation and unusual genetic variants.

 

This disorder is distinct from conditions caused by deficiencies of arylsulfatase B (Maroteaux-Lamy disease) and arylsulfatase C (steroid sulfatase deficiency).

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Gieselmann V, Ingeborg KM: Metachromatic leukodystrophy. In: Valle D, Antonarakis S, Ballabio A, Beaudet A, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed March 29, 2021. Available at https://ommbid.mhmedical.com/content.aspx?sectionid=225546629

2. Gomez-Ospina N: Arylsulfatase A deficiency. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; Updated April 30, 2020. Accessed March 29, 2021. Available at www.ncbi.nlm.nih.gov/books/NBK1130/

3. Fumagalli F, Zambon AA, Rancoita PMV, et al. Metachromatic leukodystrophy: A single-center longitudinal study of 45 patients. J Inherit Metab Dis. 2021 Sep;44(5):1151-1164. doi: 10.1002/jimd.12388.

4. van Rappard DF, Boelens JJ, Wolf NI: Metachromatic leukodystrophy: Disease spectrum and approaches for treatment. Best Pract Res Clin Endocrinol Metab. 2015 Mar;29(2):261-273. doi: 10.1016/j.beem.2014.10.001

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

Dialyzed urine is mixed with the artificial substrate p-nitrocatechol sulfate. As sulfate is released, the freed p-nitrocatechol is measured in alkaline solution at 515 nm.(Baum H, Dodgson KS, Spencer B: The assay of arylsulfatases A and B in human urine. Clin Chim Acta 1959;4:453-455; Cowan T, Pasquali M: Laboratory investigations of inborn errors of metabolism. In: Sarafoglou K, Hoffman GF, Roth KD, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1139-1158)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Tuesday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

9 to 16 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 month

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

84311

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
ARSU Arylsulfatase A, U 42726-0
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
8777 Arylsulfatase A, U 42726-0
37423 Interpretation (ARSU) 59462-2
37413 Reviewed By 18771-6

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Create a PDF

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports