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Giardia lamblia Antigen in Stool (Qualitative)

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

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

Quick summary

["A positive result may indicate an infection that needs medical evaluation or treatment."]

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

Key facts at a glance

LOINC
16899-7
Short code
G lamblia Ag Spec Ql
Synonyms
G lamblia Ag Spec Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Is Giardia Lamblia?

Giardia lamblia is a single-celled parasite that infects the intestines. It can cause chronic diarrhea, nausea, or other gastrointestinal issues. It spreads through contaminated water or food, often in areas with poor sanitation.

How Is This Test Performed?

You’ll provide a stool sample, which is tested for Giardia lamblia antigens using a sensitive immunoassay method. This detects the parasite’s presence without needing to grow it in a lab.

Why Might You Need This Test?

Your doctor may recommend this test if you have symptoms like persistent diarrhea, abdominal pain, or weight loss—especially if travel, exposure to contaminated water, or recent changes in diet are suspected causes.

What Does a Positive Result Mean?

A positive result confirms Giardia lamblia infection. This diagnosis helps guide treatment with medications like metronidazole or tinidazole to clear the parasite and relieve symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Giardia Stool Test

Frequently asked questions

What are the common symptoms of Giardia infection?
Common symptoms include watery diarrhea, stomach cramps, bloating, nausea, and sometimes a foul-smelling stool. Some people may also experience fatigue or weight loss.
How long does it take to get results from this test?
Results are usually available within 24 to 48 hours, depending on lab processing times. Your doctor will contact you once they have the outcome.
Can I take antibiotics before the test?
Yes, if you’ve been prescribed antibiotics for Giardia, you should complete the full course before retesting. Stopping early may affect the test results.
  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