Blood-tests Explained


Disclaimer:

This website is intended to assist with patient education and should not be used as a diagnostic, treatment or prescription service, forum or platform. Always consult your own healthcare practitioner for a more personalised and detailed opinion

ASO


At a Glance

Why Get Tested?

To help determine whether you have had a recent strep infection with the bacteria group A Streptococcus; to help diagnose complications resulting from a strep infection such as rheumatic fever or glomerulonephritis, a form of kidney disease

When to Get Tested?

When you have symptoms such as fever, chest pain, fatigue and shortness of breath that suggest rheumatic fever or symptoms such as edema and dark urine that are associated with glomerulonephritis, especially when you recently may have had a group A streptococcal infection that was not diagnosed and treated appropriately

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

The Test Sample

What is being tested?

Antistreptolysin O (ASO) is an antibody targeted against streptolysin O, a toxic enzyme produced by group A Streptococcus bacteria. ASO and anti-DNase B are the most common of several antibodies that are produced by the body's immune system in response to a strep infection with group A Streptococcus. This test measures the amount of ASO in the blood.

Group A Streptococcus (Streptococcus pyogenes) is the bacterium responsible for causing strep throat and a variety of other infections, including skin infections (pyoderma, impetigo, cellulitis). In most cases, strep infections are identified and treated with antibiotics, and the infections resolve.

When a strep infection does not cause identifiable symptoms, goes untreated, or is treated ineffectively, however, complications (sequelae), namely rheumatic fever and a type of kidney disease (glomerulonephritis), can sometimes develop, especially in young children. These secondary conditions have become much less prevalent in the U.S. because of routine strep testing, but they still do occur. These conditions can cause serious complications such as damage the heart, acute kidney dysfunction, tissue swelling (edema), and high blood pressure (hypertension). The ASO test can be used to help determine if these are due to a recent group A strep infection.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test