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Acid Alpha-Glucosidase, Amniotic Fluid — Catalytic Concentration

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

This prenatal test measures acid alpha-glucosidase activity in amniotic fluid and may help evaluate a fetus for Pompe disease.

Quick summary

["Reduced enzyme activity can support an evaluation for Pompe disease, but results require specialist interpretation and confirmatory testing."]

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

Key facts at a glance

LOINC
21064-1
Short code
Acid A-Glucosidase Amn-cCnc
Synonyms
Acid A-Glucosidase Amn-cCnc
Category
liver
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What is this test?

This test measures the activity of acid alpha-glucosidase, also called GAA, in amniotic fluid. GAA is an enzyme that helps break down glycogen, a stored form of sugar.

Why might I need this test?

The test may be considered when a fetus may be at risk for Pompe disease, an inherited condition in which insufficient GAA activity causes muscle and heart problems. A genetics professional can explain when this test is appropriate and how it differs from fetal genetic testing.

How is the test performed?

Amniotic fluid is collected during an amniocentesis procedure and sent to a laboratory for measurement of GAA enzyme activity. The laboratory uses an enzymatic assay, and the results are interpreted together with other prenatal findings.

How do I prepare for the test?

No food or fasting instructions apply to the laboratory measurement itself. Amniocentesis requires specific preparation and clinical counseling, so follow the instructions provided by your obstetrician or genetic counselor.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Acid Alpha-Glucosidase (Amniotic Fluid)

Frequently asked questions

What does this test measure?
It measures the activity of the acid alpha-glucosidase enzyme in amniotic fluid. Reduced activity may suggest Pompe disease.
How is the amniotic fluid obtained?
A clinician collects the fluid through amniocentesis. The procedure should be discussed with your obstetrician because it has specific risks and limitations.
Does an abnormal result confirm a diagnosis?
No. An abnormal enzyme result usually requires review and confirmation with other laboratory tests, genetic testing, or a genetics specialist.
  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