Antistreptolysin O (ASO) Test For Streptococcus Infection

Antistreptolysin O (ASO) Test For Streptococcus Infection

Antistreptolysin O (ASO) test is a blood test used to detect antibodies produced in response to a Streptococcus infection, such as strep throat. It helps diagnose recent or past infections and their potential complications.


ASO Test

Here are the basic details of the ASO Test.

Also Known As ASO Titer Test, Antistreptolysin O Test
Type Blood Test
Purpose Detect Recent Streptococcal Infections
Sample Type Serum
Preparation No
Fasting Yes
Gender Unisex
Age Group All
Normal Value 0-200 IU/mL
Reporting Time Few Days
Cost (INR) 250-650 INR*

*Price range may vary as per location, lab type, and procedure of lab test.


ASO Test Means

Antistreptolysin O (ASO) test is a blood test used to detect antibodies produced in response to a Streptococcus infection.

  • It plays a crucial role in diagnosing recent or past streptococcal infections, including strep throat.
  • ASO testing helps healthcare providers confirm the presence of a streptococcal infection and assess its severity.
  • Monitoring ASO levels can also aid in identifying potential complications related to streptococcal infections, such as rheumatic fever.
  • By providing valuable information about streptococcal infections and their effects on the body, the ASO test guides appropriate treatment and management decisions.


ASO Test Purpose

The purpose of the ASO Test is to:

  • Streptococcal infection detection.
  • Rheumatic fever diagnosis.
  • Post-streptococcal complications evaluation.
  • Antibody level assessment.
  • Inflammatory response monitoring.

ASO Test Price, Normal Range, Result, Purpose, Meaning and Interpretation - Drlogy Test


ASO Test Preparation

Here is the basic preparation for the ASO Test.


Before Test

  • You may need to refrain from eating or drinking anything for six hours before the test.
  • Inform your healthcare provider of any medications or supplements you're taking.


During Test

  • A blood sample will be collected from your arm using a needle.
  • You will be asked to remain still during the blood draw.


After Test

  • Resume your regular activities immediately.
  • You may experience mild bruising or discomfort at the needle site, which should subside shortly.
  • Await your test results, which will be communicated to you by your healthcare provider.


ASO Test Procedure

Here is the basic ASO Test Procedure.

  • Blood sample collected.
  • Needle used to draw blood.
  • Sample sent to lab.
  • ASO antibody levels assessed.
  • Results reported to healthcare provider.


ASO Test Result

  • High ASO: Suggests recent streptococcal infection risk.
  • Low ASO: May indicate no recent infection.
  • Consult a healthcare provider for interpretation.


ASO Test Report

ASO Test Report Format Example Sample Template - Drlogy Lab Report

ASO Test Report PDF


ASO Test Normal Range

Here is the normal range of the ASO Test.

ASO Level Normal Range
Adult 0-200 IU/mL


ASO Test Interpretation

Here is the Interpretation of the ASO Test.

ASO Test Result Interpretation
Within Normal Range No evidence of recent streptococcal infection
Elevated Suggests recent or ongoing streptococcal infection
Very High Indicates a significant streptococcal infection or risk of complications

Elevated or very high ASO levels may suggest a recent or ongoing streptococcal infection, including the possibility of complications like rheumatic fever.


ASO Test High Levels

Here are some possible causes of high ASO (Antistreptolysin O) test levels:

Possible Causes Effect
Recent Streptococcal Infection Elevated ASO levels can indicate a recent or ongoing streptococcal infection, such as strep throat.
Post-Streptococcal Complications High ASO levels may suggest a risk of complications like rheumatic fever or glomerulonephritis following streptococcal infections.
Autoimmune Disorders Some autoimmune diseases, such as systemic lupus erythematosus (SLE), can lead to elevated ASO levels.
Normal Variation ASO levels can naturally vary among individuals.
Medications Certain medications can interfere with ASO test results, potentially causing elevated levels.

High ASO levels are often associated with streptococcal infections and related complications. Consultation with a healthcare provider is important for a definitive diagnosis and appropriate treatment.


ASO Test Low Levels

Low ASO (Antistreptolysin O) test levels are less common, but here are some possible causes:

Possible Causes Effect
Absence of Infection Low ASO levels when there is no recent or ongoing streptococcal infection.
No Post-Streptococcal Complications Low ASO levels in the absence of complications following streptococcal infections.
Normal Variation ASO levels can naturally vary among individuals, and some may have lower baseline levels.
Medications Certain medications may interfere with ASO test results, potentially causing low levels.

Low ASO levels are not commonly observed and may not always be clinically significant. If there are concerns about ASO levels, consulting with a healthcare provider can provide a better understanding of the context and any potential implications.


Specimen Requirements For ASO Test

Here are the specimen requirements for the ASO Test.




2 ml


Red-top tube or gel-barrier tube


Separate serum from cells within one hour of collection. Transfer to a plastic transport tube before shipping.


Room temperature

Sample Stability



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Gross hemolysis; lipemia.


ASO Test is Safe?

ASO test is generally safe.

  • It requires a routine blood sample.
  • Minimal risk of complications or side effects.


When Do You Get ASO Test Results? 

  • ASO test results are typically available within a few days.
  • The exact reporting time may vary depending on the laboratory and testing facility.


ASO Test Limitation

Here is the basic limitation of ASO Test.

  • ASO test results may not be specific to a particular streptococcal infection.
  • Elevated ASO levels may persist after an infection, limiting its use in diagnosing active infections.
  • Results can vary among individuals, and false positives/negatives are possible.


ASO Test Risk Factors

Here are some of the risk factors of the ASO Test.

  • Risk factors for high ASO levels include recent streptococcal infections.
  • A history of streptococcal infections increases ASO risk.
  • Autoimmune conditions may elevate ASO levels.


Doctor Recommendations After ASO Test Result

 Here are the Doctor's recommendations or consult a specialist after the ASO Test.

ASO Result Doctor to Visit Reason
High General Practitioner Recent streptococcal infection.
Normal General Practitioner Routine health assessment.
Low General Practitioner Routine health assessment.

Please note that a General Practitioner is typically the first point of contact for routine health assessments, and they may refer you to a specialist if needed based on your specific health condition and context.


ASO Test Price

Here are the estimated ASO Test Prices in India with different top cities:


Price Range (INR)*



New Delhi


























*Prices are approximate and vary depending on a specific laboratory or healthcare facility.



Overall, ASO (Antistreptolysin O) test is a valuable tool for detecting recent streptococcal infections and assessing the risk of associated complications. Also check Drlogy Test for detailed information about all medical tests for patients, doctors, scholers and medical students.



  • Anti-streptolysin O - Wikipedia [1].
  • ntistreptolysin O titer in health and disease: levels and significance NIH [2].
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What does a positive Antistreptolysin O mean?

A positive ASO indicates exposure to streptococcal bacteria. It suggests a recent or past streptococcal infection.

What is the normal value for Antistreptolysin O?

Normal ASO levels vary but are generally below 200 Todd units per milliliter (T.U./ml) in adults.

Is ASO positive curable?

Yes, ASO positivity is curable with appropriate antibiotic treatment for the underlying streptococcal infection.

Is ASO titre 400 normal?

A titre of 400 is elevated and indicates recent or ongoing streptococcal infection. Normal levels are below 200 T.U./ml.

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