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Serum or plasma concentration of pneumococcal polysaccharide antigen (via immunoassay)

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

This test measures the presence of pneumococcal polysaccharide antigens in your blood, which can help diagnose or monitor infections caused by *Streptococcus pneumoniae* (pneumococcus).

Quick summary

["This test may help detect early or persistent pneumococcal infections."]

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

Key facts at a glance

LOINC
25280-9
Short code
S pneum Da 6B IgG 2:1 Ser-Rto
Synonyms
S pneum Da 6B IgG 2:1 Ser-Rto
Category
coagulation
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 Is This Test Done?

Your healthcare provider may order this test if you have symptoms of pneumonia, meningitis, or other serious infections, especially if you’re at higher risk (e.g., elderly, immunocompromised, or with chronic health conditions). It can also be used to guide treatment decisions in certain clinical scenarios.

What Does a Positive Result Mean?

A positive result indicates the presence of pneumococcal antigens in your blood, suggesting an active infection. This doesn’t always mean you have pneumonia but could signal other pneumococcal-related illnesses. Follow-up testing or treatment may be recommended.

What Does a Negative Result Mean?

A negative result means no detectable pneumococcal antigens were found in your sample at the time of testing. However, infections can sometimes be missed initially, so further evaluation may still be needed.

How Is This Test Performed?

A blood sample is drawn from a vein, usually in your arm. The sample is then processed in a lab to detect specific antigens using an immunoassay method, which identifies the presence of the bacteria’s unique polysaccharides.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Pneumococcal Antigen (Serum/Plasma)

Frequently asked questions

When might I need to retest?
If your initial test is positive, your provider may retest if symptoms persist or worsen. If negative, retesting may be needed if you develop new symptoms or if your condition warrants closer monitoring.
Can I eat or drink before this test?
Typically, no fasting is required for this test, but follow your provider’s instructions. Avoid alcohol or certain medications that may affect blood tests if directed.
Is there any risk or discomfort with this test?
The blood draw may cause mild discomfort or bruising at the site, but it’s generally quick and well-tolerated. Rarely, there may be a small risk of infection or excessive bleeding, but these are uncommon.
  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