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Test Code I2SWB Iduronate-2-Sulfatase, Leukocytes


Shipping Instructions


For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerated within 6 days of collection to be stabilized. Pre-analytical processing is performed Monday through Friday and Sunday. This test may be canceled if specimens are outside of stability when processing occurs. Collect and package specimens for arrival on days when processing is performed.



Necessary Information


1. Patient's age is required.

2. Reason for testing is required.



Specimen Required


Container/Tube:

Preferred: Yellow top (ACD solution B)

Acceptable: Yellow top (ACD solution A) or lavender top (EDTA)

Specimen Volume: 6 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.


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.

Secondary ID

618291

Useful For

Supporting the biochemical diagnosis of mucopolysaccharidosis II (MPS II; Hunter syndrome) in whole blood specimens

 

This test is not useful for carrier detection for MPS II.

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Specimen Type

Whole Blood ACD

Specimen Minimum Volume

5 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood ACD Refrigerated (preferred) 6 days
  Ambient  6 days

Reject Due To

Gross hemolysis Reject

Reference Values

>2.20 nmol/hr/mg protein

 

An interpretive report will be provided.

Interpretation

Abnormal results are not sufficient to establish a diagnosis of a particular disease. To verify a preliminary diagnosis based on this assay, additional biochemical or molecular genetic analyses are required.

 

When abnormal results are detected, a detailed interpretation is given, including an overview of the results and of their significance, a correlation to available clinical information, elements of differential diagnosis, recommendations for additional biochemical testing, and in vitro, confirmatory studies (enzyme assay, molecular analysis), and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.

Method Description

Leukocytes are incubated with four cocktail mixes in 96-well plates:

1. Substrate and internal standard (IS) for iduronate 2-sulfatase, heparan N-sulfatase, alpha-N-acetylglucosaminidase, N-acetylgalactosamine-sulfate, beta-galactosidase, arylsulfatase B, beta-glucuronidase, and tripeptidyl peptidase 1

2. Substrate and IS for acetyl-CoA:alpha-glucosaminide N-acetyltransferase

3. substrate and IS for N-acetylglucosamine-6-sulfatase

4. Substrate and IS for palmitoyl-protein thioesterase 1

Following overnight incubation, the plates are combined and purified by liquid-liquid extraction. The extracts are evaporated, reconstituted with mobile phase, and analyzed by tandem mass spectrometry.(Unpublished Mayo method)

Day(s) Performed

Preanalytical processing: Monday through Friday, Sunday

Testing performed: Tuesday

Report Available

8 to 15 days

Specimen Retention Time

White blood cell homogenate: 1 month

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82657

LOINC Code Information

Test ID Test Order Name Order LOINC Value
I2SWB Iduronate-2-sulfatase, WBC 24089-5

 

Result ID Test Result Name Result LOINC Value
BG765 Reason for Referral 42349-1
618291 Iduronate-2-sulfatase 24089-5
618454 Interpretation 59462-2
618453 Reviewed By 18771-6