Anti-Streptolysin O Antibody (ASO)

The Anti-Streptolysin O Antibody (ASO) test contains 1 test with 1 biomarker.

Brief Description: The Anti-Streptolysin O (ASO) Antibody test is a blood test that measures the levels of antibodies against Streptolysin O, a toxin produced by Group A Streptococcus bacteria. These bacteria are responsible for various infections, including strep throat and certain skin infections. The test helps in diagnosing and monitoring infections caused by these bacteria.

Also Known As: ASLO Test, ASO Test, ASO Antibody Test, Strep A Test, Streptococcus Group A Test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: No preparation required

When is an Anti-Streptolysin O Antibody test ordered?

When a patient exhibits symptoms that a medical professional believes could be related to a condition brought on by a prior strep infection, the ASO test is requested. When symptoms start to show, which typically happens a few weeks after a sore throat or skin infection when the bacteria are no longer in the throat or on the skin, the treatment is recommended.

For acute and convalescent ASO titers, the test may be carried out twice, with samples being taken roughly two weeks apart. This is carried out to ascertain whether the antibody level is increasing, decreasing, or staying the same.

What does an Anti-Streptolysin O Antibody blood test check for?

The hazardous enzyme streptolysin O, which is generated by group A Streptococcus bacteria, is the target of the antibody known as antistreptolysin O. The most prevalent antibodies generated by the body's immune system in connection to a strep infection with group A Streptococcus are ASO and anti-DNase B. The level of ASO in the blood is determined by this test.

A Group The bacterium that causes strep throat and a number of other illnesses, including skin infections, is streptococcus. Antibiotics are usually used to diagnose and treat strep infections, and the illnesses usually go away.

However, complications, such as rheumatic fever and a specific form of kidney disease, can occasionally arise from strep infections, particularly in young children, when they do not produce any distinguishable symptoms, are ignored, or are ignored but ineffectively treated. Due to frequent strep testing, these secondary diseases are now far less common in the United States, but they still do happen. Serious complications from these disorders include heart damage, acute renal dysfunction, tissue edema, and high blood pressure. If they are brought on by a recent group A strep infection, the ASO test can be used to assist identify the cause.

Lab tests often ordered with an Anti-Streptolysin O Antibody test:

When an ASO test is ordered, it's usually part of a broader evaluation of streptococcal infection and its complications. Here are some tests commonly ordered alongside it:

  1. Complete Blood Count (CBC):

    • Purpose: To evaluate overall blood health.
    • Why Is It Ordered: To check for signs of infection (like elevated white blood cells) and to assess general health.
  2. Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP):

    • Purpose: To measure markers of inflammation.
    • Why Is It Ordered: To assess the level of inflammation, which can be elevated in rheumatic fever and other post-streptococcal diseases.
  3. Anti-DNAse B Antibody:

    • Purpose: To detect antibodies against another enzyme produced by group A Streptococcus.
    • Why Is It Ordered: To complement the ASO test, especially in cases where ASO might be negative but streptococcal infection is still suspected.
  4. Urinalysis:

    • Purpose: To analyze components of the urine.
    • Why Is It Ordered: To check for signs of kidney involvement, such as protein or blood in the urine, which can occur in post-streptococcal glomerulonephritis.
  5. Kidney Function Test:

    • Purpose: To evaluate kidney function.
    • Why Is It Ordered: To monitor kidney health, particularly in cases suspected of developing post-streptococcal glomerulonephritis.

These tests, when ordered alongside an ASO test, provide a comprehensive evaluation of a recent streptococcal infection and its potential complications, including rheumatic fever and glomerulonephritis. They are crucial for diagnosing, monitoring, and managing these conditions effectively. The specific combination of tests will depend on the individual’s symptoms, clinical findings, and medical history.

Conditions where an Anti-Streptolysin O Antibody test is recommended

  • Strep Throat: ASO levels are elevated after a strep throat infection.
  • Scarlet Fever: A complication of strep throat, characterized by a rash and high fever.
  • Rheumatic Fever: Elevated ASO levels increase the risk of developing rheumatic fever, which affects the heart, joints, and other tissues.

How does my health care provider use an Anti-Streptolysin O Antibody test?

The main purpose of the ASO test is to identify recent group A streptococcal strep infections.

Antibiotics are typically used to diagnose and treat strep infections, and the illnesses usually go away. However, in certain persons, particularly in young children, complications, such as rheumatic fever and glomerulonephritis, might arise when they do not result in observable symptoms and/or go untreated. Therefore, if a patient has a recent history of sore throat or a confirmed streptococcal infection and symptoms suggestive of rheumatic fever or glomerulonephritis.

What do my Anti-Streptolysin O Antibody test results mean?

About a week to a month after the initial strep infection, ASO antibodies start to develop. After reaching a high 3 to 5 weeks after the sickness, the level of ASO antibody gradually decreases, but it may still be detected months after the strep infection has cleared up.

It is highly likely that the person tested did not recently contract strep throat if the ASO is negative or present at extremely low titers. This is particularly true if a sample collected 10 to 14 days later is negative as well as if a negative anti-DNase B test results. There is a slight chance that someone with a strep infection complication won't have an increased ASO. This is particularly valid in the case of glomerulonephritis, which can arise following a cutaneous strep infection.

It is likely that the person who was tested has recently had strep infection if they have a high antibody titer or an increasing ASO titer. ASO titers that are initially high and then start to drop indicate that an infection has started and might be on the verge of going away.

The ASO test does not foretell the type or severity of the disease, nor does it foretell if there would be problems after a strep infection. An increased ASO level may be utilized to support the diagnosis of glomerulonephritis or rheumatic fever in cases where symptoms are already present.

The Most Common Questions About the Anti-Streptolysin O Antibody test:

Clinical Utility and Interpretation

What is the Anti-Streptolysin O Antibody test, and what is its main purpose?

The Anti-Streptolysin O Antibody test is used to detect antibodies against Streptolysin O, a toxin produced by Group A Streptococcus bacteria. The primary purpose of the ASO test is to diagnose and confirm recent infections caused by these bacteria, such as strep throat or rheumatic fever.

How do healthcare providers interpret the results of the Anti-Streptolysin O Antibody test?

Results are interpreted based on the levels of ASO antibodies in the blood. Elevated levels typically indicate a recent or ongoing infection with Group A Streptococcus. However, interpretation can be complex, as levels may vary among individuals, and other infections or conditions can influence ASO levels.

Clinical Applications and Diagnoses

When might a healthcare provider recommend the Anti-Streptolysin O Antibody test?

A healthcare provider might recommend the ASO test if a patient has symptoms suggestive of an infection caused by Group A Streptococcus, especially if complications like rheumatic fever or glomerulonephritis are suspected.

Can the Anti-Streptolysin O Antibody test be used to monitor treatment for strep infections?

Yes, the ASO test may be used to monitor the response to treatment for strep infections. A decrease in ASO levels following treatment can indicate that the infection is resolving.

Comparative Insights

How does the Anti-Streptolysin O Antibody test compare to other methods of diagnosing streptococcal infections?

The ASO test is typically used in conjunction with other diagnostic methods, such as throat cultures or rapid antigen tests. While the ASO test can indicate a recent streptococcal infection, it does not identify the bacteria directly. Cultures and rapid tests are generally more useful for acute diagnosis, whereas the ASO test can provide evidence of recent or past infections.

Understanding Limitations and Challenges

What are the limitations of the Anti-Streptolysin O Antibody test?

The ASO test has several limitations, including:

  • It does not confirm the presence of Group A Streptococcus, only the body's response to it.
  • The ASO levels can vary significantly between individuals, and timing post-infection affects levels.
  • Other infections or conditions can influence ASO levels, leading to potential false positives or negatives.

What might cause falsely elevated or reduced results in the Anti-Streptolysin O Antibody test?

Falsely elevated results might occur due to other infections or inflammatory conditions. On the other hand, some individuals may naturally have low or undetectable ASO levels even after a streptococcal infection, leading to falsely reduced or negative results.

Additional Questions and Insights

Is there a specific time frame in which the Anti-Streptolysin O Antibody test should be performed after suspected infection?

The ASO levels usually rise 1 to 3 weeks after the onset of a streptococcal infection and may remain elevated for several months. The test is typically most informative when performed a few weeks after the onset of symptoms.

Why might the Anti-Streptolysin O Antibody test be performed alongside other streptococcal antibody tests?

The ASO test might be performed alongside other streptococcal antibody tests, such as anti-DNase B, to increase the diagnostic accuracy and provide a more comprehensive view of the body's immune response to streptococcal infections. Different antibodies might rise and fall at different times, so testing for multiple antibodies can enhance the assessment.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: AntiStreptolysin O Antibody ASO, ASO, Strep A,ASO, Streptolysin-O Antibody

Anti-Streptolysin O

*Process times are an estimate and are not guaranteed. The lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.

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