Cryptococcal Antigen in Serum/Plasma (1,3-β-D-glucan-based)
This test checks for the presence of cryptococcal antigen, a fungal marker often linked to infections caused by *Cryptococcus neoformans* or *Cryptococcus gattii*. It helps diagnose cryptococcal meningitis or other cryptococcal infections.
["A positive result may indicate a fungal infection requiring urgent medical evaluation."]
Key facts at a glance
- LOINC
- 31304-9
- Short code
- C pneum IgM Ser-aCnc
- Synonyms
- C pneum IgM Ser-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82784
- 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 This Test Measures
The test detects specific fungal antigens (1,3-β-D-glucan) produced by certain types of cryptococcal fungi. These antigens are released when the fungi are active in your body. The test is highly sensitive for detecting cryptococcal infections, especially in people with weakened immune systems.
Why It’s Done
Your healthcare provider may order this test if you have symptoms of meningitis (such as severe headache, fever, stiff neck) or other signs of a fungal infection, particularly if you have HIV/AIDS, a weakened immune system, or other risk factors for cryptococcal infections.
Who Needs This Test
This test is most commonly recommended for people with HIV/AIDS, transplant recipients, or those with other conditions that weaken the immune system. It may also be used in patients with unexplained neurological symptoms or high-risk exposures to cryptococcal fungi.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into a vein (usually in your arm) to draw a blood sample. The process is quick and typically painless. If you’re nervous, let your healthcare provider know.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A positive result strongly suggests a cryptococcal infection and should prompt immediate medical attention. Cryptococcal meningitis can be life-threatening if untreated. A negative result means no detectable antigen in your blood at this time, but follow-up testing may still be needed if symptoms persist.
Short name
Crypto Antigen
Frequently asked questions
What does a positive result mean?
Can this test be done at home?
How soon will I get my results?
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