Antibody to Streptococcal Group A Bacteria (ASO) – Serum, Qualitative or Quantitative
This test measures the presence of antibodies produced in response to Streptococcus group A bacteria, often linked to strep throat or other infections. It helps diagnose past or current infections and guides treatment decisions.
["Detects antibodies from strep infections to guide treatment and monitor recovery."]
Key facts at a glance
- LOINC
- 30149-9
- Short code
- ASO Ab sp1 Ser-aCnc
- Synonyms
- ASO Ab sp1 Ser-aCnc
- 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 ASO test identifies antibodies (specifically anti-streptolysin O antibodies) your immune system makes when exposed to certain bacteria, such as those causing strep throat. These antibodies can remain in your blood for months or years after the infection has cleared.
Why It’s Ordered
Your healthcare provider may order this test if you have symptoms like sore throat, fever, rash, or swollen lymph nodes, especially if strep throat is suspected. It can also help evaluate recurrent infections or assess complications like rheumatic fever.
How the Test Works
A blood sample is drawn from a vein in your arm. The serum is tested to detect the presence of ASO antibodies using an immunoassay method, which may involve detecting antibody levels through color change or other indicators.
What to Expect Before the Test
No special preparation is needed, but inform your provider about any medications, recent infections, or allergies. Avoid strenuous activity 24 hours before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated ASO levels suggest a recent streptococcal infection. While not always definitive, they support a diagnosis of strep throat or other streptococcal-related conditions. Persistently high levels may indicate chronic exposure or autoimmune conditions. Always consult your provider for interpretation.
Short name
ASO Antibody Test
Frequently asked questions
How long does it take to get results?
Can I have this test if I’m pregnant?
Does this test show if I currently have strep?
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