ASO Test: What It Is, Procedure, Preparation and Results

If you've been told you need an ASO Titre test, you might be wondering what exactly that is. This article will explain everything you need to know about the ASO Titre test, the procedure, preparation, and results.

The blood test used to detect strep infection is called the antistreptolysin O (ASO) titer test. Some illnesses caused by this bacteria are:

• Strep throat
• Scarlet fever
• Glomerulonephritis
• Rheumatic fever, which can affect the heart, joints, or bones
• Bacterial endocarditis is an infection of the inner lining of your heart

What is The ASO Titre Test?

Antistreptolysin O (ASO) is an antibody developed to fight the harmful enzyme streptolysin O produced by group A Streptococcus bacteria. A blood test called an antistreptolysin O (ASO) Titre measures antibodies against streptolysin O.  Antibodies are proteins made by the body to protect it from invaders like bacteria and viruses. These antibodies are specific to the bacteria they need to fight. The ASO Titre Test measures the level of antibodies in the blood to determine if they are high enough to fight off an infection.

Why Do You Need The ASO Titre Test?

The ASO Titre test is a blood test that measures the level of antibodies in your blood. If you exhibit signs of a previous group A streptococcus infection, you will require the test. Even weeks or months after the strep infection has cleared up, the ASO antibody may still be present in the blood. The ASO Titre test is used to diagnose certain conditions and infections spreading to the throat, skin, middle ear, tonsils, sinuses, and blood that may get infected as a result. Most likely, an antibiotic will be used to treat and cure a strep infection. You could, however, experience subsequent issues if you don't experience any symptoms or if the condition is not fully treated. If your healthcare practitioner believes you may be experiencing one of the following problems, an ASO titre blood test may be necessary.

Bacterial endocarditis is an infection of the heart's inner lining due to bacteria or other pathogens getting into the bloodstream and going to the heart. The germs adhere to heart tissue or damaged heart valves. This potentially fatal inflammation of the inner lining of the heart's chambers and valves is known as endocarditis. There are a few signs such as:

• Chills or a fever
• Fatigue
• Cough
• Nausea
• Sweats during night
• Aching joints and muscles
• Breathing problems

Glomerulonephritis is a kidney condition when the kidneys' glomeruli (minuscule filters) are harmed. It may make it more difficult for your kidneys to eliminate fluid and waste from your body. Kidney failure can also happen in serious circumstances. The following symptoms can be present:

• Urine containing blood
• Tiredness
• Nausea and rashes
• High blood pressure
• Pain in joints or stomach
• Decreased or increased urination
• Swelling on the face or joints

Rheumatic fever: According to medical professionals, it is your body's immune reaction to a prior strep or scarlet fever infection. A deadly inflammatory disorder called rheumatic fever can harm your heart, joints, brain, skin, and joints. Rheumatic fever symptoms can include:

• Knees, ankles, elbows, and wrists have sore, achy joints.
• Fever
• Chest pain, breathlessness, and a rapid heartbeat are all cardiac symptoms.
• Tiredness
• Unexpected jerking
• Although uncommon, there may be lumps under the skin near the joints.
• Pink circles with clear centres are unusual, but there are some in the rash.

Scarlet fever affects children between the ages of five and fifteen and may have these symptoms, which are listed below:

• A skin rash that is red and looks like a sunburn
• Red lines around the neck, elbows, knees, armpits, and groin area
• A flushed face with a pale lip ring.
• Red and rough tongue with a coating of white

What is The Procedure for ASO Titre Test?

The procedure for ASO Titre Test is to get a blood sample from the patient, separate the blood cells from the liquid portion of the blood, and then incubate them with an antibody that will bind to a particular antigen.

Certain precautions required before this test are that you might need to skip food and liquids for six hours before the test. Before this test, your doctor could advise you to cease using a particular medicine.

ASO Titre Normal Range

The ASO Titre normal range is considered within 0-200 for adults and below 100 for children aged 5 years and less. A low titre may, under certain circumstances, represent the immune system's effective eradication of pathogenic microorganisms. A high titre, on the other hand, can be the result of lingering antibodies from an earlier infection or failed attempts to assemble antigen-antibody complexes. High ASO test results mean you got a streptococcus infection.

What Are The Uses of the ASO Test?

The ASO test is a simple blood test that serves several important purposes. Here are some of the ASO test uses:

• Diagnosing recent streptococcal infections, especially when direct bacterial cultures are negative or unavailable.
• Identifying serious complications related to streptococcal infections, such as rheumatic fever, post-streptococcal glomerulonephritis, and scarlet fever.
• Supporting clinical evaluation in patients showing symptoms of these complications, as elevated ASO titre test results suggest a recent infection that may have triggered the condition.

How to Prepare for the ASO Test

The ASO test preparation is straightforward and requires minimal effort from the patient:

• Fasting is generally not necessary before the test. But in some cases, especially for qualitative ASO tests, fasting for 6-7 hours may be recommended to improve result accuracy.
• Inform your doctor about any medications you are taking, particularly antibiotics or corticosteroids, as these can influence antibody levels and affect test accuracy.

What to Expect During the ASO Test

The ASO test procedure is quick, simple, and minimally invasive:

• A healthcare professional will draw a small blood sample, usually from a vein in your arm, using a needle and syringe.
• The collected blood sample is then sent to a laboratory where the concentration of antistreptolysin O antibodies is measured quantitatively or qualitatively.

Factors Influencing Test Results

Several factors can impact ASO test results, potentially leading to inaccurate or misleading findings:

• Recent use of antibiotics or corticosteroids can suppress antibody production, causing false-negative results.
• The timing of the test is crucial. Antibody levels usually rise 1-3 weeks post-infection, peaking at 3-5 weeks. Testing too early may miss elevated titres.
• Individual variations in immune response can affect antibody production.
• The presence of other infections or immune disorders might influence antibody levels.
• Improper sample handling or testing techniques can compromise result accuracy.

What Are The Benefits of the ASO Test?

With several key advantages in diagnosing and managing streptococcal infections, the ASO test benefits are plenty:

• Provides objective evidence of a recent streptococcal infection when throat cultures are negative or unavailable.
• Aids in diagnosing and monitoring serious complications like rheumatic fever and glomerulonephritis.
• Guides treatment decisions by confirming an immune response to streptococcal infection.
• Non-invasive and relatively inexpensive compared to other diagnostic methods.

ASO Titre positive signs include the following symptoms:

• Fever and Fatigue
• Skin rashes
• Elevated blood pressure
• Swelling (oedema)
• Swelling and pain in joints
• Nodules under the skin that don't hurt
• Shortness of breath, chest pain, palpitations, and heart inflammation (carditis).

ASO Titre Positive Treatment

Increased ASO Titre levels in the blood may harm the heart and joints. Penicillin is typically used to treat patients with elevated ASO Titre levels.

Conclusion

In conclusion, there are many factors that could result from any of the conditions listed in the article with symptoms that can affect someone's titre levels. Therefore, it is important to understand your titre levels and know what to do next if you have high titre levels.

FAQs

What is the ASO test used for?

The ASO test detects antibodies against streptolysin O, a toxin produced by group A Streptococcus. It indicates a recent or past streptococcal infection and helps diagnose related complications such as rheumatic fever and glomerulonephritis.

What does positive ASO mean?

A positive or elevated ASO test report means your body has produced antibodies in response to a recent streptococcal infection. While it alone does not confirm an active infection, it supports the diagnosis when correlated with clinical symptoms.

What if my ASO is high?

High ASO titre test levels suggest a recent streptococcal infection and may indicate an increased risk or presence of complications like rheumatic fever or kidney inflammation. Further clinical evaluation and possibly treatment may be necessary.

What is the ASO test in urine?

The ASO test is typically performed on blood samples, not urine. Urine tests do not measure ASO antibodies as they circulate in the blood.

What does the ASO test measure?

The ASO test measures the concentration of antistreptolysin O antibodies in the blood. These antibodies are produced by the immune system in response to the streptolysin O toxin released by group A Streptococcus bacteria.

Is fasting required for the ASO test?

In most cases, fasting is not necessary before an ASO test. However, some laboratories may recommend fasting for 6-7 hours before a qualitative ASO test to enhance result accuracy.

What conditions can the ASO test diagnose?

The ASO test aids in diagnosing recent streptococcal infections and their associated complications, including rheumatic fever, post-streptococcal glomerulonephritis, scarlet fever, and other streptococcal infections.

How long does it take to get ASO test results?

ASO test reports are typically available within 1-2 days, depending on the laboratory's processing time and workload.

What does a normal ASO test result mean?

A normal or low ASO test result indicates the absence of a recent streptococcal infection or that antibody levels have returned to baseline following a past infection.

How often should the ASO test be repeated?

The frequency of ASO test repetition depends on the specific clinical situation and the healthcare provider's judgement.