Ordering Recommendation

Preferred test to evaluate symptomatic patients for Tay-Sachs disease or Sandhoff disease. Can identify carriers of Tay-Sachs disease. Can identify carriers of Sandhoff disease. For individuals who are pregnant, use oral contraceptives, have severe liver or autoimmune disease, or have a previous inconclusive HEX A enzyme serum/plasma test, the preferred test is Hexosaminidase A percent and Total Hexosaminidase in Leukocytes (2008125) to avoid false-positive results.




Quantitative Fluorometry




2-9 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Yellow (ACD). Also acceptable: Plain red.

Specimen Preparation

Transfer 1 mL Plasma or Serum to an ARUP Standard Transport Tube (Min: 0.2 mL) or transport 3 mL whole blood (Min: 1 mL). Do not transfer whole blood to other containers.

Storage/Transport Temperature

Plasma/Serum: Frozen Whole blood: Room temperature. 

Unacceptable Conditions

Clinical information is needed for appropriate interpretation. Additional required information includes age, gender, diet (e.g.TPN therapy), drug therapy, and family history. Biochemical Genetics Patient History Form is available on the ARUP Web site at https://www.aruplab.com/patienthistory or by contacting ARUP Client Services.


Plasma/Serum: Ambient: 3 days; Refrigerated: 7 days; Frozen: 1 month Whole blood: Ambient: 3 days; Refrigerated: 3 days; Frozen: Unacceptable

Reference Interval

Available Separately
Reference Interval
No Hexosaminidase A Percent 55-76 percent
No Hexosaminidase Total Effective August 17, 2015
600-1050 nmol hydrolyzed/hr/mL

Interpretive Data

Refer to report.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Compliance Category

Laboratory Developed Test (LDT)


This test is used for the diagnosis of Tay-Sachs disease and can also be used to identify carriers for this disorder. Carrier screening is offered to individuals of Ashkenazi Jewish descent because of the high incidence of the disease in this population. Pregnant women or women using oral contraceptives cannot be tested using plasma or serum because of high false-positives rates. In serum samples, false positives can also be caused by several other conditions, including severe liver disease and autoimmune diseases. Testing in leukocytes should be used in these cases.

Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
2008122 Hexosaminidase Total 1954-7
2008123 Hexosaminidase A Percent 12914-8
2008124 Hexosaminidase Plasma/Serum Interp 93479-4
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • Plasma and serum hexosaminidase Hexosaminidase A and Total, plasma or serum
Hexosaminidase A Percent and Total Hexosaminidase, Plasma or Serum (Change effective as of 02/22/22: Refer to 3004486 in the February Hotline)