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Giardia duodenalis Antigen (Stool)

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

This test detects the presence of Giardia duodenalis, a microscopic parasite that can cause intestinal infections, often leading to symptoms like diarrhea, stomach cramps, or bloating.

Quick summary

["A stool test to check for Giardia parasite infection."]

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

Key facts at a glance

LOINC
21570-7
Short code
T gondii IgG Ser Ql Dye Test
Synonyms
T gondii IgG Ser Ql Dye Test
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
dye-test
CPT
82784
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 Does This Test Measure?

The test looks for specific antigens (proteins) produced by the Giardia parasite in your stool. These antigens help confirm if you have an active infection caused by Giardia duodenalis, which can live in contaminated water or food.

Why Might You Need This Test?

Your healthcare provider may recommend this test if you have symptoms like persistent diarrhea, stomach pain, or bloating, especially after traveling to areas with poor sanitation, or if you’ve been exposed to contaminated water.

How Is the Test Done?

You’ll need to provide a fresh stool sample (usually collected in a provided container) to a lab. The sample is tested using a method that detects Giardia antigens, often through immunoassay techniques.

What Are Possible Results?

A positive result means the test found Giardia antigens in your stool, suggesting an active infection. A negative result means no detectable antigens were found, but other causes of symptoms may still exist.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Giardia duodenalis is a common parasite that can cause gastrointestinal issues, including chronic diarrhea, malabsorption, and dehydration. Early detection is important to guide treatment and prevent spread to others.

Short name

Giardia stool test

Frequently asked questions

How soon will I get my results?
Results are typically available within 1 to 3 business days, depending on lab processing times. Your healthcare provider will discuss the results with you during your follow-up visit.
Can I eat or drink before the test?
Yes, you can eat and drink normally before providing the stool sample. However, avoid using laxatives or enemas, as they may affect the test results.
What if my test is positive?
If your test is positive for Giardia, your doctor may prescribe an antibiotic to treat the infection. Follow their instructions carefully, and they may recommend retesting after treatment to confirm clearance.
  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