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Cryptosporidium Stool Antigen Test (Qualitative)

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

This test detects the presence of Cryptosporidium parasites in your stool, which can cause diarrhea and other gastrointestinal symptoms. It helps diagnose an infection that may require treatment.

Quick summary

["This test checks for a common parasite that can cause stomach upset and long-term health issues in some people."]

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

Key facts at a glance

LOINC
31794-1
Short code
Cryptosp Ag Spec Ql
Synonyms
Cryptosp Ag Spec Ql
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
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
CPT
85610
SNOMED
396252006
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

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you’ve experienced persistent diarrhea, abdominal pain, or other symptoms that could be linked to a parasitic infection. It’s also used in certain high-risk groups, such as people with weakened immune systems (e.g., from HIV/AIDS, chemotherapy, or organ transplants).

What to Expect Before the Test

No special preparation is needed. You’ll provide a fresh stool sample in a provided container. If you’re taking certain medications (like antibiotics), let your provider know, as they may affect results.

How the Test Works

The test uses an immunoassay (likely a qualitative method) to detect Cryptosporidium antigens in your stool. Antigens are small parts of the parasite that trigger an immune response. The test identifies these if present, helping confirm an infection.

What the Results Mean

A positive result means Cryptosporidium parasites were found in your stool, strongly suggesting an infection. A negative result means no parasites were detected at the time of testing, but infection could still be present. Follow-up testing or additional samples may be needed for confirmation.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

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.

Clinical Significance

Short name

Crypto Stool Test (Qual)

Frequently asked questions

What does a positive result mean?
A positive result indicates you likely have a Cryptosporidium infection, which can cause watery diarrhea, stomach cramps, nausea, or vomiting. In people with weakened immune systems, symptoms may be severe or last longer. Treatment focuses on supportive care (like staying hydrated) and may include medications to reduce symptoms. In others, the infection often resolves on its own.
What if I have a negative result but still feel sick?
A negative result means no parasites were detected in this sample, but other causes of your symptoms could include viruses, bacteria, or other parasites. If you continue to have symptoms, your provider may order additional tests or retest later. Sometimes, symptoms can take days or weeks to appear after exposure.
How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on lab processing times. If you have urgent symptoms, discuss your timeline with your provider to see if immediate results are possible.
  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