Description

Antistreptolysin O (ASO) is an antibody that targets streptolysin O, a toxic enzyme produced by Streptococcus group A bacteria. The most common antibodies produced by the body’s immune system in response to a group A Streptococcus infection are ASO and anti-DNase B. This test determines the level of ASO in the blood.

A Group Streptococcus (Streptococcus pyogenes) is the bacterium that causes strep throat and other infections, including skin infections (pyoderma, impetigo, cellulitis). Strep infections are typically identified and treated with antibiotics, and the infections resolve.

You can request this test when symptoms appear, usually in the weeks following a sore throat or skin infection and when the bacteria are no longer present in the throat or on the skin.

Rheumatic fever symptoms may include:
– Fever – Joint swelling and pain in multiple joints, particularly the ankles, knees, elbows, and wrists, which sometimes move from one joint to the next – Small, painless nodules under the skin – Rapid, jerky movements (Sydenham’s chorea)
– Skin rash – The heart can become inflamed (carditis) and produce no symptoms, but it can also cause shortness of breath, heart palpitations, or chest pain.

Some glomerulonephritis symptoms include:
– Fatigue and low energy – Reduced urine output – Bloody urine – Rash – Joint pain – Swelling (edema) – High blood pressure

These symptoms, however, can be seen in other conditions as well.  

This test can be done twice, about one to two weeks apart, to see if the antibody level is increasing, decreasing, or staying the same.