Hexosaminidase A Percent and Total Hexosaminidase, Plasma or Serum
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.
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Yellow (ACD). Also acceptable: Plain red. 
Specimen Preparation
Do not transfer whole blood to other containers. Transport 3 mL whole blood (Min: 1 mL) or transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.2 mL) 
Storage/Transport Temperature
Whole blood: Room temperature.  Serum: Frozen 
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 http://www.aruplab.com/patienthistory or by contacting ARUP Client Services. 
Whole blood: Ambient: 3 days; Refrigerated: 3 days; Frozen: Unacceptable
Serum: Ambient: 3 days; Refrigerated: 7 days; Frozen: 1 month 
Reference Interval
Available Separately
Reference Interval
NoHexosaminidase A Percent55-76 percent
NoHexosaminidase TotalEffective August 17, 2015
600-1050 nmol hydrolyzed/hr/mL

Interpretive Data
Refer to report.

Statement B: 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. 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
Component Test Code*Component Chart NameLOINC
2008122Hexosaminidase Total1954-7
2008123Hexosaminidase A Percent12914-8
2008124Hexosaminidase Plasma/Serum Interp
* 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 view this test within the Laboratory Test Directory found at www.aruplab.com
  • Plasma and serum hexosaminidase Hexosaminidase A and Total, plasma or serum