Giardia lamblia antigen in stool (qualitative immunoassay)

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

This test detects the presence of Giardia lamblia parasites in your stool using an antibody-based method. Giardia is a common intestinal parasite that can cause diarrhea, stomach cramps, and other digestive symptoms.

Quick summary

["A positive result may indicate an infection that requires medical evaluation."]

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

Key facts at a glance

LOINC: 110302-7
Short code: G lamblia Ag Msmt Stl
Synonyms: G lamblia Ag Msmt Stl
Category: chemistry
Sample: stool
Container: Clean container
Units: N/A
Fasting: false
Population: adult
Sex: all
Age range: 18–65 years
Specimen volume: 5 g
Stability: Refrigerated: 24h, Frozen: 7d
TAT: 4–24 hours
Order: routine

What This Test Measures

The test looks for specific proteins (antigens) produced by Giardia lamblia, a microscopic parasite that can infect your intestines. These antigens are released when the parasite is active in your stool. The immunoassay method detects these antigens to confirm if you have an active infection.

How the Test Works

Your stool sample is tested using an immunoassay technique that identifies Giardia antigens. This method is highly sensitive and specific for detecting current infection rather than past exposure.

When You Might Need This Test

Your healthcare provider may recommend this test if you have symptoms like persistent diarrhea, bloating, gas, or stomach pain that could be caused by Giardia. It’s also used in travelers’ diarrhea evaluations or in settings where parasite infections are common.

What to Expect Before the Test

No special preparation is needed for this test. You’ll provide a fresh stool sample, typically collected in a provided container. If you’re unsure about timing, ask your provider—some tests may prefer early morning samples.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Giardia stool test (qualitative)

Frequently asked questions

Why might my doctor order this test?

A positive result confirms an active Giardia infection, which can lead to symptoms like chronic diarrhea, abdominal pain, or malnutrition if untreated. Treatment focuses on antiparasitic medications and managing symptoms. A negative result means no active infection was detected, but symptoms may still be due to other causes.

What does a positive result mean?

A positive result indicates you have an active Giardia infection. This requires medical treatment with prescription medications to clear the parasite. Follow-up testing may be needed to confirm the infection is resolved.

Can I still have symptoms even if the test is negative?

Yes, symptoms may persist if the infection was mild, intermittent, or cleared without treatment. Other causes of similar symptoms (like food poisoning, IBS, or other infections) could also explain ongoing issues. Discuss your symptoms with your provider for further evaluation.

Sources

1
MedlinePlus — Laboratory TestsSource
2
Lab Tests OnlineSource
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