Antibody to Pneumocystis jirovecii (IgG) – Serum
This test measures the presence of antibodies against the fungus *Pneumocystis jirovecii*, which can cause a lung infection called Pneumocystis pneumonia (PCP). It helps identify past exposure or infection, often used in patients at high risk, such as those with weakened immune systems.
["This test helps doctors assess risk for or track past exposure to a lung infection linked to weakened immunity."]
Key facts at a glance
- LOINC
- 27119-7
- Short code
- Deprecated S pneum23 Ab sp2 Ser-mCnc
- Synonyms
- Deprecated S pneum23 Ab sp2 Ser-mCnc
- 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 Is Done
Your doctor may order this test if you have symptoms like cough, shortness of breath, or fever and are at higher risk for PCP. High-risk groups include people with HIV/AIDS, those undergoing chemotherapy, transplant recipients, or those with certain immune disorders. It’s also used to monitor patients who have already been treated for PCP to ensure they no longer carry the infection.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into your arm or vein to draw blood. The process usually takes a few minutes. If you’re nervous, let your healthcare provider know—they can help make it more comfortable.
What the Results Mean
Positive results indicate the presence of antibodies, suggesting past exposure to *Pneumocystis jirovecii*. However, antibodies alone don’t always mean you currently have an active infection. Your doctor will consider your medical history, symptoms, and other test results to interpret the results accurately.
Possible Side Effects
Most people experience only mild discomfort or bruising at the injection site. Rarely, you might feel lightheaded or have a slight reaction to the needle. If you experience severe pain, swelling, or signs of infection (like redness or fever), contact your doctor right away.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Pneumocystis jirovecii IgG Antibody
Frequently asked questions
How often should I get this test?
What does a positive result mean for my health?
Can I still get PCP even if my antibody test is negative?
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