Antistreptolysin O (ASO)

What is the purpose of the ASO test?

The primary purpose of the ASO test is to assist in determining whether a recent infection caused by group A Streptococcus (commonly known as strep) has:

1. This led to the development of glomerulonephritis, a kidney disease.
2. Triggered rheumatic fever in a person exhibiting signs and symptoms.

This test may be performed individually or in conjunction with an anti-DNase B test, another diagnostic tool for detecting recent streptococcal infections.

Typically, strep infections are identified and effectively treated with antibiotics, resulting in the resolution of the infection. However, in cases where these infections remain unnoticed, untreated, or asymptomatic, complications can arise, particularly in young children. Consequently, the ASO test is recommended if an individual displays symptoms suggestive of rheumatic fever or glomerulonephritis and has a recent history of a sore throat or a confirmed streptococcal infection.

It's worth noting that the use of the ASO test has decreased in the United States as the incidence of post-streptococcal complications has declined.

When the ASO test is ordered by physicians?

The ASO test is requested when an individual presents symptoms that raise suspicion of a condition resulting from a prior streptococcal infection. Typically, this test is ordered as symptoms manifest, often occurring several weeks after a sore throat or skin infection, at a point when the streptococcal bacteria are no longer present in the throat or on the skin.

What other testing might be done besides ASO?

If your healthcare provider suspects rheumatic fever, they may recommend additional tests such as anti-DNAse B, anti-hyaluronidase, or anti-streptomyces to evaluate the condition further.

What are Some symptoms of rheumatic fever?

Some symptoms of rheumatic fever may include:

• Fever
• Joint swelling and pain in more than one joint, especially in the ankles, knees, elbows and wrists, sometimes moving from one joint to another.
• Small, painless nodules under the skin
• Rapid, jerky movements (Sydenhams chorea)
• Skin rash
• Sometimes, the heart can become inflamed (carditis); this may not produce any symptoms but also lead to shortness of breath, heart palpitations, or chest pain.

What are Some symptoms of glomerulonephritis?

Some symptoms of glomerulonephritis may include:

• Fatigue, decreased energy
• Decreased amount of urine
• Bloody urine
• Rash
• Joint pain
• Swelling (edema)
• High blood pressure

These symptoms can be seen in other conditions.