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Giardia duodenalis Antigen Detection by Immunoassay (Stool Probe)

Published: August 9, 2026Updated: August 17, 2026

This test checks for 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 simple stool test to detect a common parasite causing digestive issues."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
90299-9
Short code
Giardia DNA Stl Ql NAA+probe
Synonyms
Giardia DNA Stl Ql NAA+probe
Category
chemistry
Sample
stool
Container
Clean container
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
CPT
84484
SNOMED
302774002
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
TAT
4–24 hours
Order
routine

What This Test Measures

The test detects Giardia duodenalis antigens in your stool. Giardia is a parasite that can infect the intestines, sometimes causing long-term digestive problems. This probe method identifies specific proteins (antigens) from the parasite to confirm an infection.

How the Test Works

Your stool sample is analyzed using an immunoassay (a lab test that uses antibodies to detect specific substances). If Giardia is present, the antibodies will bind to its antigens, triggering a visible reaction that confirms the infection.

Why You Might Need This Test

Doctors 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.

Common Symptoms

Symptoms of Giardia infection can include watery diarrhea, nausea, vomiting, stomach cramps, gas, and bloating. Some people may not have symptoms at all but can still spread the parasite.

Reference range

Adult: 10-40 U/LN/A

Specimen: stool

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Giardia Stool Test (Screen)

Frequently asked questions

How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing schedule. Your healthcare provider will discuss the results with you.
What if my test is positive?
A positive result means you have an active Giardia infection. Treatment usually involves prescription antibiotics to kill the parasite. Follow your doctor’s advice for a full course of medication and proper hygiene to prevent spreading it to others.
Can I still spread Giardia even if I don’t have symptoms?
Yes, Giardia can be spread without symptoms. Practice good hand hygiene, avoid contaminated water, and avoid sharing personal items to help prevent spreading the infection.
  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 17, 2026. · Read our editorial policy