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Hexosaminidase Levels Blood Test

Last updated May 26, 2019

Approved by: Krish Tangella MD, MBA, FCAP

The Hexosaminidase Levels Blood Test helps determine the levels of hexosaminidases A and B in blood.

What are other Names for this Test? (Equivalent Terms)

  • Hexosaminidase A and B Levels Blood Test
  • Hexosaminidase A and Hexosaminidase B Levels Blood Test
  • Total Hexosaminidase Levels Blood Test

What is Hexosaminidase Levels Blood Test? (Background Information)

  • Hexosaminidase is a group of enzymes, made up of hexosaminidase A and hexosaminidase B, which breaks down a type of fat called ganglioside. Hexosaminidases are found in the brain, where the majority of gangliosides reside
  • Problems with hexosaminidase A leads to the accumulation of gangliosides in neural cells, which causes these cells to swell, greatly interfering with their function. This results in the symptoms of Tay-Sachs disease
  • Sandhoff’s disease is a type of Tay-Sachs disease that progresses much faster than Tay-Sachs disease. It results from problems with both hexosaminidases A and B
  • The instructions for making hexosaminidase A and hexosaminidase B enzymes reside on the genetic blueprint. Mutations in the genes associated with hexosaminidase A and B leads to defective hexosaminidase production, which causes Tay-Sachs disease and Sandhoff’s disease
  • The Hexosaminidase Levels Blood Test helps determine the levels of hexosaminidases A and B in blood. It is used to diagnose Tay-Sachs disease and Sandhoff’s disease

What are the Clinical Indications for performing the Hexosaminidase Levels Blood Test?

Following are the clinical indications for performing the Hexosaminidase Levels Blood Test:

  • Family history of Tay Sachs disease or Sandhoff’s disease
  • Ashkenazi Jewish ancestry
  • Mental development problems
  • Muscular weakness
  • Blindness

How is the Specimen Collected for the Hexosaminidase Levels Blood Test

Following is the specimen collection process for Hexosaminidase Levels Blood Test:

Sample required: Blood

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Hexosaminidase Levels Blood Test Result?

  • A low percentage (less than 55%) of hexosaminidase A may indicate Tay-Sachs disease
  • A low amount (less than 5 units/l) of total hexosaminidase may indicate Sandhoff’s disease

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Certain factors, such as pregnancy, interfere with the results of the Hexosaminidase Levels Blood Test. Hence, most laboratories do not perform the test on pregnant women

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

The following DoveMed website link is a useful resource for additional information:



Please visit our Laboratory Procedures Center for more physician-approved health information:


References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: March 30, 2016
Last updated: May 26, 2019