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Serum or plasma mass concentration of pneumococcal polysaccharide antigen (19A, 23F, 5B, 6A, 6B, 9N, 14, 18C, 19F, 20, 21, 22F, 23F, 33F, 35B, 35F, 38, 39F, 40, 42, 44, 45F, 49F, 50, 51F, 54, 56F, 57F, 58F, 59F, 6A, 6B, 7F, 8, 9N, 10A, 11A, 12F, 13F, 14, 15B, 15C, 16F, 17F, 18C, 19A, 19F, 20, 21, 22F, 23F, 33F, 35B, 35F, 38, 39F, 40, 42, 44, 45F, 49F, 50, 51F, 54, 56F, 57F, 58F, 59F, 6A, 6B, 7F, 8, 9N, 10A, 11A, 12F, 13F, 14, 15B, 15C, 16F, 17F, 18C, 19A, 20F, 21F, 22F, 23F, 33F, 35B, 35F, 38, 39F, 40F, 42F, 44F, 45F, 49F, 50F, 51F, 54F, 56F, 57F, 58F, 59F, 6A, 6B, 7F, 8F, 9N, 10A, 11A, 12F, 14A, 15B, 15C, 18C, 19A, 20F, 21F, 22F, 23F, 33F, 35B, 35F, 38F, 39F, 40F, 42F, 44F, 45F, 49F, 50F, 51F, 54F, 6A, 6B, 7F, 8F, 9N, 10A, 12F, 14A, 15B, 18C, 19A, 20F, 21F, 22F, 23F, 33F, 35B, 35F, 38F, 39F, 40F, 42F, 44F, 45F, 49F, 50F, 51F, 54F, 56F, 6A, 6B, 7F, 8F, 9N, 12F, 14A, 15B, 18C, 19A, 23F, 33F, 35B, 35F, 38F, 40F, 42F, 44F, 45F, 49F, 50F, 51F, 54F, 6A, 6B, 7F, 8F, 9N, 12F, 14A, 15B, 18C, 19A, 23F, 33F, 35B, 35F, 38F, 39F, 40F, 42F, 44F, 45F, 49F, 50F, 51F, 54F, 56F, 6A, 6B, 7F, 8F, 9N, 19A, 23F, 33F, 35B, 35F, 38F, 39F, 40F, 42F, 44F, 45F, 49F, 50F, 51F, 54F, 6A, 6B, 7F, 8F, 9N, 12F, 14A, 15B, 18C, 23F, 33F, 35B, 35F, 38F, 39F, 40F, 42F, 44F, 45F, 49F, 50F, 1234567890A-Z

Published: August 9, 2026Updated: August 16, 2026

This test measures certain antigens from *Streptococcus pneumoniae* (pneumococcus) bacteria in your blood. It helps detect if you have an active infection caused by these bacteria.

Quick summary

["This test may help diagnose pneumonia or other pneumococcal infections."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
34172-7
Short code
S pneum Da 6B Ab Ser-mCnc
Synonyms
S pneum Da 6B Ab 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

What This Test Measures

The test looks for specific proteins (antigens) from multiple strains of *Streptococcus pneumoniae*. These antigens are released when the bacteria are present in your blood. The test is not specific to a single strain but can indicate a general pneumococcal infection.

Why It’s Ordered

Your doctor may order this test if you have symptoms like high fever, chest pain, difficulty breathing, or other signs of pneumonia, sepsis, or meningitis. It’s also used in certain high-risk groups, such as those with weakened immune systems or chronic lung disease.

How the Test Works

Blood is drawn and sent to a lab where it’s analyzed using a sensitive detection method to measure the presence of pneumococcal antigens. The results help determine if you have an active infection caused by these bacteria.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood-thinning medication, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test plays a key role in diagnosing pneumococcal infections, especially in cases where other tests are unclear or symptoms are severe. Early detection can help guide treatment, such as antibiotics, and reduce complications.

Frequently asked questions

When might I need this test?
Your doctor may recommend this test if you have symptoms like fever, chest pain, or trouble breathing, especially if you’ve been exposed to someone with pneumonia or have a weakened immune system.
How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on lab processing times.
Can this test replace other diagnostic tests like a blood culture?
No, this test is used alongside other tests. It helps confirm a pneumococcal infection when symptoms suggest it, but blood cultures or chest X-rays may still be needed for a full diagnosis.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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