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Test Code .Aryl A p Arylsulfatase A for I Cell

Important Note

Only orderable as "I Cell, Mucolipidosis II"; includes Arylsulfatase A and Hexosaminidase in serum or plasma.

For Metachromatic Leukodystrophy, order Arylsulfatase A (Metachromatic leukodystrophy)

Clinical System Name

.Arylsulfatase A, plasma


I Cell

Arylsulfatase A, plasma

.Aryl A p






Enzyme analysis of total hexosaminidase, % hexosaminidase A, and arylsulfatase A in plasma or serum for diagnosis of  I-Cell disease (ML II).

Sample Requirements

Specimen: Whole Blood

Container(s): Dark Green/Sodium Heparin tube, Yellow/ACD A or B, Serum from Gold SST or Red top tubes

Preferred Vol:  2.0 mL

Minimum Vol: 1.0 mL


Processing Instructions

Reject due to:

Spin: Y


Temp:-20 C

Storage location: Biochemical Genetics Box -20 C



Specimen should be spun and aliquoted within 2 hours of collection.



Off-site collection:  Transport  to Laboratory immediately.


Specimen Type Temperature Time
Aliquoted Serum/Plasma Refrigerated

7 days

  Freezer (-20 C)-preferred 1 month



STAT Performed TAT
N Weekly 7  days

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

Performing Laboratory

Seattle Children's Laboratory    


Department:  Biochemical Genetics

Phone Number: 206-987-2216



Reference Range


Specimen Type Normal Range

Total hexosaminidase (serum)

932-1844 nmol/hr/mL
% Hex A 54.7 - 70%
Arylsulfatase A (serum/plasma) 0 - 100 nmol/hr/mL

Carrier testing not performed


Method:  Enzymatic/Fluorometric; 4-methylumbelliferyl substrate with heat inactivation, and spectrophotometric.

Analytical Volume:


CPT Codes



Biochemical Genetics Requisition


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

Clinical Utility

Patients with I Cell disease (mucolipidosis type II) have extreme elevation of serum/plasma total Hexosaminidase and Arylsulfatase A.


Carrier testing by enzyme analysis is not available.