Serum Concentration of *Pneumococcus* (Streptococcus pneumoniae) Antigen
This test measures the presence of *Pneumococcus* bacteria in your blood serum, often used to diagnose serious infections like pneumonia or sepsis caused by this bacterium.
["This test helps doctors identify if *Pneumococcus* is in your blood, which can guide treatment decisions."]
Key facts at a glance
- LOINC
- 51807-6
- Short code
- C pneum IgM Ser IA-aCnc
- Synonyms
- C pneum IgM Ser IA-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- 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 Is Done
Your doctor may order this test if you have symptoms like high fever, difficulty breathing, confusion, or rapid heartbeat, especially if you have a weakened immune system, recent head trauma, or are at higher risk for *Pneumococcus* infections. It can also be used in certain hospital settings to monitor patients with suspected infections.
How the Test Works
The test detects specific proteins (antigens) from *Pneumococcus* bacteria in your blood serum. If these antigens are present, it suggests active infection. The method used is typically **immunoassay** (often chemiluminescent or fluorescence-based), which is highly sensitive for detecting low levels of the bacteria.
Sample Collection and Preparation
A blood sample is drawn from a vein in your arm. The blood is processed to separate serum (the liquid part without clots) for testing. This test does not require fasting or special preparation.
What to Expect Before or After the Test
You may feel slight discomfort or bruising at the injection site after the blood draw. Avoid vigorous activity for a few hours afterward. If you experience excessive bleeding or signs of infection (redness, swelling, fever), contact your healthcare provider.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Pneumococcal Antigen Test
Frequently asked questions
This test is critical for diagnosing *Pneumococcus* infections early, which can prevent complications like organ damage or death. It is especially useful in patients who cannot be easily tested with other methods (e.g., those with severe illness or limited mobility). Results help doctors tailor antibiotics to target the specific bacteria causing your infection.
Results are typically available within **24 to 48 hours**, depending on your lab’s processing schedule. Your doctor will discuss the findings with you during your follow-up visit.
While this test detects *Pneumococcus* antigens in the blood, it is not the primary test for diagnosing pneumonia. Doctors may also use chest X-rays, sputum cultures, or other imaging studies to confirm pneumonia caused by *Pneumococcus* or other pathogens.
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