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Cryptosporidium antigen in stool (qualitative)

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

This test checks for the presence of Cryptosporidium, a microscopic parasite that can cause diarrhea, especially in people with weakened immune systems.

Quick summary

["A positive result may indicate an infection that requires medical evaluation."]

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

Key facts at a glance

LOINC
31793-3
Short code
Cryptosp Ag Stl-aCnc
Synonyms
Cryptosp Ag Stl-aCnc
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
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 doctor may recommend this test if you have persistent diarrhea, especially if it lasts more than a few days, or if you’re at higher risk for infections, such as having a weakened immune system (e.g., due to HIV/AIDS, chemotherapy, or other conditions). It’s also used to diagnose cryptosporidiosis in travelers returning from areas with known outbreaks or in patients with unexplained gastrointestinal symptoms.

What to Expect Before the Test

No special preparation is needed. You’ll provide a sample of your stool in a provided container. If you’re using a stool collection kit, follow the instructions carefully to ensure the sample remains fresh and accurate.

What the Test Results Mean

A positive result means Cryptosporidium parasites were detected in your stool, suggesting an infection. A negative result means no parasites were found, but other causes of diarrhea could still be present. Follow-up testing or additional evaluation may be needed based on your symptoms and medical history.

Possible Side Effects or Considerations

There are no known side effects from providing a stool sample. If you experience discomfort or unusual symptoms after the test, contact your healthcare provider.

Reference range

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

Specimen: stool

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.

◆Associated findings1

Short name

Stool Cryptosporidium Test

Frequently asked questions

What does a positive result mean?
A positive result confirms the presence of Cryptosporidium parasites in your stool, indicating an active infection. This typically requires medical attention to address symptoms and prevent complications, such as dehydration.
Can I eat or drink normally before the test?
Yes, you can eat and drink as usual before the test. No special diet or fasting is required.
How long does it take to get the results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing schedule. Your doctor will discuss the results with you during your follow-up visit.
  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