Hexosaminidase A Percent and Total Hexosaminidase in Leukocytes
Ordering Recommendation

Preferred initial test to diagnose suspected Tay-Sachs disease or identify carriers of Tay-Sachs disease. Use for individuals who are pregnant, use oral contraceptives, have severe liver or autoimmune disease, or had previously inconclusive HEX A enzyme serum/plasma level. Can detect Sandhoff disease.

Quantitative Fluorometry
2-9 days
New York DOH Approval Status
This test is New York DOH approved.
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Yellow (ACD). 
Specimen Preparation
Do not transfer whole blood to other containers. Transport 3 mL whole blood. (Min: 1.0 mL) 
Storage/Transport Temperature
Room temperature. Also acceptable: Refrigerated. 
Unacceptable Conditions
Whole blood received greater than 3 days from collection. Grossly hemolyzed specimens. 
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 or by contacting ARUP Client Services. 
Ambient: 3 days; Refrigerated: 3 days; Frozen: Unacceptable 
Reference Interval
Effective November 18, 2013

Greater than or equal to 63 percent
Interpretive Data
Refer to report.

Compliance Statement B: For laboratory developed tests not using a RUO kit, and for FDA approved, cleared or 510(k) exempt assays with alterations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

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.
Hotline History
View Hotline History
Component Test Code*Component Chart NameLOINC
2008126Hexosaminidase A Percent in Leukocytes23825-3
2008127Hexosaminidase Total, Leukocytes50759-0
2008128Hexosaminidase in Leukocytes Interp21328-0
* 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.
  • HEXA enzyme testing
  • Hexosaminidase A and Total, leukocytes