Clinics and Departments

Laboratory Services

Lab Dept:

Chemistry

Test Name:

HEXOSAMINIDASE A & TOTAL HEXOSAMINIDASE, SERUM

General Information

Lab Order Codes:

HEXAT

Synonyms:

B-N-Acetylglucosaminidase; GM2 Gangliosidosis; Sandhoff Carrier Screening; Tay Sachs Carrier Screening

CPT Codes:

Enter code and description

Test Includes:

Total Hexosaminidase level reported in nmol/min/mL, Hexoaminidase A reported as a % of total.

Logistics

Test Indications:

Diagnosing Tay-Sachs disease, carriers of Tay-Sachs, Sandhoff’s disease, and carriers of Sandhoff’s disease.

Lab Testing Sections:

Chemistry - Sendouts

Referred to:

Mayo Medical Laboratories (MML Test: 8774/NAGS)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

8 – 15 days, performed on Tuesdays

Special Instructions:

For females of child-bearing age: If females wish screening for carrier status of hexoaminidase A deficiency, they must be tested prior to pregnancy. Serum assay results are often ambiguous on pregnant females and will not be run.

Specimen

Specimen Type:

Blood

Container:

Red top tube

Draw Volume:

3 mL (Minimum: 1.5 mL) blood

Processed Volume:

1 mL (Minimum: 0.5 mL) serum

Collection:

Routine venipuncture

Special Processing:

Lab Staff: Centrifuge specimen. Remove serum aliquot and place into a screw-capped plastic vial. Ship and store at frozen temperatures.

Patient Preparation:

None

Sample Rejection:

Warm specimens; samples from pregnant females; mislabeled or unlabeled specimens

Interpretive

Reference Range:

Hexosaminidase A and Total, Serum (nmol/min/mL)

≤15 years:

≥20 nmol/min/mL

≥16 years:

10.4 – 23.8 nmol/min/mL

Percent A (%)

≤15 years:

20 – 90%

≥16 years:

56 – 80%

Interpretation is provided with report.

Critical Values:

N/A

Limitations:

This test cannot be performed on pregnant females.

GM2 activator deficiency (CM2-gangliosidosis, AB variant) is a rare disorder with clinical features similar to Tay-Sachs and Sandhoff diseases; however, levels of both hexosaminidase A and B are normal. GM2 activator deficiency cannot be identified through testing offered at Mayo Medical Laboratories.

Methodology:

Heat inactivation, Fluorometric, Automated

References:

Mayo Medical Laboratories July 2013

Updates:

7/18/2013: Note change in units change for Hexoaminidase A, previously reported as U/L. Also reference ranges have been amended for age groups.



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