Pneumococcal Group Antigen in Serum (Mass Concentration)
This test measures the presence of antibodies against *Streptococcus pneumoniae* (pneumococcus) in your blood. These antibodies help your immune system recognize and fight off this common bacterial cause of pneumonia, meningitis, and other infections.
["Helps identify if your body has developed immunity against pneumococcal bacteria, useful before vaccination or in monitoring immune response."]
Key facts at a glance
- LOINC
- 31300-7
- Short code
- C pneum IgA Ser-aCnc
- Synonyms
- C pneum IgA 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
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you’re at higher risk for pneumococcal infections—such as people with weakened immune systems, those with chronic health conditions (like heart or lung disease), or those who’ve recently received a pneumococcal vaccine. It may also be used to assess immune response after vaccination.
How the Test Works
Blood is drawn and analyzed to detect specific antibodies (antigens) produced by your immune system in response to pneumococcal bacteria. The test measures these antibodies in your serum, often using a sensitive immunoassay method to detect even small amounts.
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. If you’re on blood thinners or have a history of bleeding issues, let your provider know.
What the Results Mean
Results are qualitative (positive or negative) and indicate whether antibodies against pneumococcal are present. A positive result suggests your immune system has recognized the bacteria, while a negative result means no detectable antibodies were found.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Pneumococcal Antibody Screening
Frequently asked questions
How does this test help doctors?
What if my results are positive?
Could this test be affected by recent illness?
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