Serum Antigen Specific to Pneumocystis jirovecii (Pneumocystis jirovecii Antigen)
This test detects antibodies in your blood that may indicate past or recent exposure to *Pneumocystis jirovecii*, a fungus responsible for a rare but serious lung infection called pneumocystis pneumonia (PCP). It helps doctors assess risk in certain patient groups.
["Helps identify possible exposure to PCP, especially in immunocompromised individuals."]
Key facts at a glance
- LOINC
- 13161-5
- Short code
- Deprecated S pneum23 Ab sp1 Ser-aCnc
- Synonyms
- Deprecated S pneum23 Ab sp1 Ser-aCnc
- Category
- coagulation
- 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
Why This Test Might Be Ordered
Your doctor may recommend this test if you have a weakened immune system (e.g., due to HIV/AIDS, chemotherapy, or other conditions like organ transplants) and are at higher risk for PCP. It’s also used in screening or monitoring patients with known risk factors.
How the Test Works
A small blood sample is taken to check for antibodies produced by your immune system in response to *Pneumocystis jirovecii*. These antibodies suggest prior infection or exposure, though they don’t confirm active disease.
What to Expect Before the Test
No special preparation is needed. You may have a slight bruise or discomfort at the needle site, but most people find it quick and painless. If you’re on blood-thinning medication, let your doctor know.
What to Expect After the Test
You can return to your normal activities immediately. Watch for any unusual bleeding or signs of infection (e.g., fever, redness) at the injection site. Report any severe reactions right away.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Positive results suggest a history of *Pneumocystis jirovecii* exposure, which may warrant further evaluation for PCP or other lung conditions. Negative results rule out recent exposure in high-risk patients but don’t guarantee immunity. Always discuss results with your healthcare provider for personalized guidance.
Short name
Pneumocystis jirovecii Antibody Test
Frequently asked questions
Will this test show if I currently have PCP?
Can I get this test if I’m not immunocompromised?
How long does it take to get 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