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Acid Alpha-Glucosidase — Catalytic Concentration

Published: August 9, 2026Updated: August 16, 2026

Measures acid alpha-glucosidase enzyme activity, which is commonly evaluated when evaluating a possible diagnosis of Pompe disease.

Quick summary

["Low acid alpha-glucosidase activity can be associated with Pompe disease, but results usually require clinical and confirmatory testing."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
1814-3
Short code
Acid A-Glucosidase Smn-cCnc
Synonyms
Acid A-Glucosidase Smn-cCnc
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

This test measures the activity of acid alpha-glucosidase, also called GAA. This enzyme breaks down a complex sugar called glycogen within lysosomes, the cells' recycling compartments.

Why might I need this test?

The test may be ordered when muscle weakness, breathing difficulty, heart enlargement, or other findings raise concern for Pompe disease, a rare inherited storage disorder. It may also be used to monitor certain people who already have the condition.

How is the test performed?

A laboratory measures GAA enzyme activity in a patient sample. Blood-derived samples may be used for screening, while other samples and confirmatory laboratory studies may be needed to establish a diagnosis.

How do I prepare for the test?

Special preparation may depend on the specimen and laboratory method. Follow the testing instructions, and tell the healthcare team about recent blood transfusions or other treatments that could affect enzyme measurements.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low acid alpha-glucosidase activity may be associated with Pompe disease, particularly when compatible symptoms or other laboratory findings are present. Results can vary with the specimen and testing method, so an abnormal screening result generally requires confirmatory testing and clinical interpretation. Genetic testing may be recommended to clarify a diagnosis.

Short name

Acid Alpha-Glucosidase Activity

Frequently asked questions

What does this test measure?
It measures the activity of the acid alpha-glucosidase enzyme, which helps cells break down stored glycogen.
What condition is this test often used to evaluate?
It is commonly used in the evaluation of Pompe disease, an inherited disorder that can affect muscles, breathing, and the heart.
Does a low result confirm Pompe disease?
Not by itself. The result must be interpreted with the specimen type, symptoms, other tests, and often confirmatory genetic testing.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy