Antibody to Streptococcus Group A (ASO) – Quantitative
This test measures the level of antibodies your body produces in response to a bacterial infection caused by *Streptococcus group A* (commonly called Group A Streptococcus, or GAS). It helps identify past or recent infections that may have led to conditions like strep throat or rheumatic fever.
["This test helps doctors diagnose or monitor infections linked to Group A Streptococcus bacteria."]
Key facts at a glance
- LOINC
- 45228-4
- Short code
- ASO Ab Ser-mCnc
- Synonyms
- ASO 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
Why Is This Test Done?
Your healthcare provider may order this test if you have symptoms like sore throat, fever, rash, or joint pain that could suggest a Group A Streptococcus infection. It may also be used to check if you’ve recovered from such an infection or to monitor complications like rheumatic fever.
What Does a Positive Result Mean?
A positive result indicates your body has produced antibodies against Group A Streptococcus, suggesting you’ve likely had an infection in the past. However, it doesn’t always mean you’re currently infected—some people may have lingering antibodies even after recovery.
What Does a Negative Result Mean?
A negative result means your body hasn’t produced detectable antibodies to Group A Streptococcus at this time, which could mean you’re not currently infected or haven’t been exposed recently.
How Is This Test Performed?
A blood sample is drawn from a vein in your arm. The sample is then tested in a lab to measure the concentration of ASO antibodies using an immunoassay method.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: This test is primarily used to diagnose or confirm a history of Group A Streptococcus infection, such as strep throat or scarlet fever. Elevated levels may also be associated with post-streptococcal complications like acute glomerulonephritis or rheumatic fever, though other tests may be needed to confirm these conditions.
Short name
ASO Antibody Test
Frequently asked questions
What Are the Common Symptoms of Group A Streptococcus Infection?
How Long Does It Take to Get Results?
Can This Test Be Done at Home?
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