Cryptosporidium Stool Antigen Test (Qualitative)
This test checks for the presence of Cryptosporidium, a microscopic parasite that can cause diarrhea, especially in people with weakened immune systems.
["A positive result may indicate an infection that requires medical evaluation."]
Key facts at a glance
- LOINC
- 39534-3
- Short code
- Cryptosp Ag Stl Ql IF
- Synonyms
- Cryptosp Ag Stl Ql IF
- Category
- coagulation
- Sample
- stool
- Container
- Clean container
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- if
- CPT
- 85610
- SNOMED
- 396252006
- Specimen volume
- 5 g
- Stability
- Refrigerated: 24h, Frozen: 7d
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may recommend this test if you have persistent diarrhea, especially if it lasts more than a few days, or if you have symptoms like stomach cramps, nausea, or weight loss. It’s also used in people with HIV/AIDS, organ transplants, or other conditions that weaken the immune system, as they’re more likely to get sick from parasites like Cryptosporidium.
What to Expect Before the Test
No special preparation is needed. You’ll likely be asked to collect a sample of your stool in a container provided. If you’re using a stool collection kit at home, follow the instructions carefully to ensure the sample is fresh and representative.
How the Test Works
The test detects specific proteins (antigens) from Cryptosporidium in your stool. These proteins are released when the parasite is active. The test uses a simple visual method to identify these proteins, often with a color change in a test strip or card.
What the Results Mean
A positive result means that Cryptosporidium antigens were found in your stool, suggesting an active infection. A negative result means the test did not detect these antigens, but other causes of your symptoms could still be responsible. Follow-up testing or additional evaluation may be needed if symptoms persist.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Cryptosporidium is a common cause of watery diarrhea in people with compromised immune systems. Early diagnosis is important to manage symptoms, prevent dehydration, and avoid spreading the infection to others. Treatment focuses on supportive care, such as staying hydrated, and may include medications to reduce symptoms in some cases.
Short name
Cryptosporidium Stool Test
Frequently asked questions
How long does it take to get the results?
Can I eat or drink before the test?
What if my test is positive?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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