Anti-Streptolysin-O (ASO) Quantitative Test
About Anti-Streptolysin-O (ASO) Quantitative Test
| Field | Value |
|---|---|
| Also Known As | ASO, ASO Titre, ASOT, Anti-streptolysin O Titre, Strep A Antibodies Test |
| Sample Type | Venous blood (serum) |
| Fasting Required | Not required; some laboratories prefer 6 to 8 hours of fasting |
| Report Time | 1 to 2 days |
| Recommended For | All ages; commonly children aged 5 to 15 years and adults with suspected post-streptococcal complications |
| Price | Starting at ₹240 |
What Is an Anti-Streptolysin-O (ASO) Quantitative Test?
The Anti-Streptolysin-O (ASO) Quantitative Test measures the level of ASO antibodies in the blood. These antibodies are produced by the immune system in response to a toxin released by the Group A Streptococcus bacteria. Doctors order this test when they suspect complications from a past streptococcal infection, such as strep throat that was untreated or inadequately treated. Also known as the ASO titre or Strep A antibodies test, it uses a small blood sample drawn from a vein.
What Does an Anti-Streptolysin-O (ASO) Quantitative Test Measure?
The test measures a single key marker in the blood. Here is what it tracks and why it matters:
| Parameter | What It Tells You |
|---|---|
| ASO Antibody Level (Titre) | Indicates whether the body has recently mounted an immune response against Group A Streptococcus bacteria. Levels begin rising 1 to 3 weeks after infection, peak at 3 to 5 weeks, and gradually fall over 6 to 12 months. |
Why Is an Anti-Streptolysin-O (ASO) Quantitative Test Done?
A doctor may order this test for several reasons, from investigating unexplained symptoms to confirming a suspected post-infection complication.
Common Symptoms That May Require This Test
- Sore throat that persists or recurs
- Joint pain and swelling, particularly in the knees or ankles
- Unexplained fever
- Skin rash, including a sandpaper-like texture
- Dark or blood-tinged urine
- Chest pain or discomfort
- Persistent fatigue without a clear cause
Conditions This Test Can Help Detect
The ASO titer result helps support the diagnosis of several post-streptococcal conditions, including:
- Rheumatic fever (inflammation affecting the heart, joints, and other tissues)
- Post-streptococcal glomerulonephritis (a type of kidney inflammation)
- Scarlet fever
- Bacterial endocarditis (infection involving the lining of the heart)
- PANDAS (Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections)
- Guttate psoriasis triggered by streptococcal infection
How to Prepare and What to Expect
Preparing for an ASO quantitative test is straightforward. The steps below cover everything you need to know before your appointment.
Do You Need to Fast?
Fasting is not required for this test. Some laboratories may prefer that you avoid eating for 6 to 8 hours beforehand, so follow the specific instructions given by your doctor or the laboratory.
Practical Tips Before Your Test
- Tell your doctor about all medications you are currently taking, especially antibiotics or corticosteroids (anti-inflammatory steroids), as these can affect results
- Drink plenty of water before your appointment to make blood collection easier
- No special dietary restrictions apply to this test
- Wear clothing with sleeves that roll up easily to allow comfortable access to the arm
Step-by-Step Procedure
- A trained phlebotomist (blood collection professional) cleans the inner side of your arm with an antiseptic wipe.
- A soft elastic band is tied around your upper arm to make the veins easier to see and access.
- A small needle is gently inserted into a vein, and a brief blood sample is collected into a tube.
- The needle is removed, and light pressure is applied to the puncture site to stop any bleeding.
- A small adhesive bandage is placed over the site.
- The labelled sample is dispatched to the laboratory for analysis.
Factors That Can Affect Accuracy
- Recent use of antibiotics or corticosteroids, which can suppress antibody production and cause a falsely low result
- Testing too early after infection, before antibody levels have had time to rise
- Conditions such as liver disease, tuberculosis, or elevated beta-lipoprotein levels, which may cause a falsely high result
- Breakdown of red blood cells in the sample (haemolysis) during collection
- Certain conditions, including myeloma, liver disease, and autoimmune disease with elevated rheumatoid factor, may interfere with results
Understanding Your Anti-Streptolysin-O (ASO) Quantitative Test Results
Results should always be reviewed alongside your symptoms and medical history. The table below shows generally accepted reference ranges for the ASO titer.
| Parameter | Age Group | Normal Range |
|---|---|---|
| ASO Antibody Level | Children under 5 years | Less than 100 IU/mL |
| ASO Antibody Level | Children 5 to 17 years | Up to 640 IU/mL |
| ASO Antibody Level | Adults (general guideline) | Less than 200 IU/mL (Todd units) |
These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain health conditions and medications can alter the outcome of the test. Your doctor will take these into account when reviewing your result.Patients with liver disease, tuberculosis, or high beta-lipoprotein levels may show an elevated ASO reading even without a recent streptococcal infection. Those taking antibiotics or corticosteroids before the test may show lower-than-expected levels, even if a past infection has occurred. Conditions such as myeloma and autoimmune diseases with elevated rheumatoid factor can also interfere with the result.It is also worth noting that in cases of streptococcal skin infections (such as impetigo), the ASO response tends to be weaker than in throat infections. A small proportion of patients with rheumatic fever may show normal ASO levels.
How to Maintain Healthy Levels
General habits that support your wellbeing and reduce the risk of streptococcal complications include:
- Complete any prescribed antibiotic course for strep throat fully, even if you feel better before finishing the medication
- Practise regular hand washing, particularly during cold and flu season, to reduce the spread of bacterial infections
- Attend any follow-up tests your doctor recommends, especially if your initial ASO titer was elevated
Lupin Diagnostics Anti-Streptolysin-O (ASO) Quantitative Test Price and Home Collection
The Anti-Streptolysin-O (ASO) Quantitative Test is available at Lupin Diagnostics starting at approximately ₹240, with home sample collection offered across cities in India.
| City | Approximate Price (₹) |
|---|---|
| Mumbai | ₹550 |
| Bangalore | ₹550 |
| Chennai | ₹550 |
| Hyderabad | ₹550 |
| Kolkata | ₹550 |
| Pune | ₹550 |
| Ahmedabad | ₹550 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
- Select the test on the Lupin Diagnostics website.
- Choose your city and preferred time slot.
- Opt for home sample collection by a certified phlebotomist, or visit your nearest Lupin Diagnostics centre.
- Receive your report via email or WhatsApp within the stipulated turnaround time.
Home Collection
Home sample collection for the ASO test is available across multiple cities in India. All samples are processed in NABL-accredited laboratories staffed by qualified technologists. Your digital report is accessible via email or WhatsApp once ready.
Frequently Asked Questions
The ASO test checks whether your body has mounted an immune response to a recent streptococcal infection. Doctors use it mainly to identify complications such as rheumatic fever or kidney inflammation (glomerulonephritis) that can develop weeks after an untreated or poorly managed strep infection.
Fasting is generally not required. Some laboratories may prefer that you fast for 6 to 8 hours beforehand. Follow the guidance given by your doctor or the diagnostic centre at the time of booking.
A throat swab or rapid strep test detects an active, current infection. The ASO titer test, by contrast, identifies a past infection by measuring antibodies, which take at least a week to become detectable in the blood. The two tests serve different purposes and are not interchangeable.
A raised ASO titer suggests that your body produced antibodies in response to a recent streptococcal infection. A high result alone does not confirm a specific disease. Your doctor will consider it alongside your symptoms, clinical examination, and any other test results before drawing a conclusion.
Yes. Antibiotics and corticosteroids can reduce ASO antibody levels, which may produce a falsely normal result. Always inform your doctor about any medications or supplements you are taking before the test.
Repeating the test roughly 10 to 14 days after the first reading helps determine whether antibody levels are rising, falling, or stable. A rising level over two readings is generally considered a stronger indicator of recent streptococcal infection than a single result.
Yes. Home collection for the Anti-Streptolysin-O (ASO) Quantitative Test is available through Lupin Diagnostics. A certified phlebotomist visits your home at your chosen time, and the sample is sent directly to an accredited laboratory for processing.
Anti-Streptolysin-O (ASO) Quantitative Test
