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Giardia intestinalis stool antigen test (qualitative immunoassay)

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

This test detects the presence of Giardia intestinalis antigens in your stool, helping identify if you have an infection caused by this common intestinal parasite.

Quick summary

["Checks for Giardia parasite in stool using a simple blood test-like method."]

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

Key facts at a glance

LOINC
108163-7
Short code
Giardia Stl Ql Micro
Synonyms
Giardia Stl Ql Micro
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
microscopy-light
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 looks for specific proteins (antigens) produced by *Giardia intestinalis*, a microscopic parasite that can cause gastrointestinal symptoms like diarrhea, stomach cramps, and bloating. It’s not a culture test, so it doesn’t grow the parasite in a lab, but it’s highly sensitive for detecting current infection.

How the Test Works

A small stool sample is collected, and a chemical reaction (immunoassay) identifies the Giardia antigens if they’re present. Results are typically reported as positive or negative.

When You Might Need This Test

Your doctor may recommend this test if you’ve had symptoms like persistent diarrhea, abdominal pain, or bloating—especially if you’ve traveled to areas with poor sanitation or have been exposed to contaminated water. It’s also used in screening for travelers or those in high-risk groups.

What to Expect Before the Test

No special preparation is needed, but you may be asked to collect a fresh stool sample (usually in a container provided). If you’re on antibiotics, ask your doctor first, as they could affect results.

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.

◆Associated findings1

Short name

Giardia stool test (qualitative)

Frequently asked questions

How soon will I get my results?
Results are usually available within 24 to 48 hours, depending on your lab’s processing schedule. Your doctor will discuss them with you.
What does a positive result mean?
A positive result means Giardia antigens were found in your stool, indicating an active infection. This doesn’t confirm the parasite’s cause of your symptoms, but it guides treatment decisions. Follow-up tests or cultures may be needed for further evaluation.
Can I take this test at home?
No, this test requires a sample collected by a healthcare provider or in a lab setting. Some clinics offer at-home stool collection kits, but results must be sent to a lab for analysis.
  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