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Antistreptolysin O

Medically reviewed by Last updated on Apr 2, 2024.

What is antistreptolysin O?

Antistreptolysin O (ASO) is an antibody. This test is done to see if you have the ASO antibody in your blood. An antibody is a protein that is made by your immune system. The ASO antibody shows if you have had an infection caused by the Streptococcus bacteria. Some illnesses are caused by a previous Streptococcus bacterial infection.

How do I get ready for the test?

Your healthcare provider will tell you when to have your blood test done. The blood test may be done before or after eating. Ask your healthcare provider if you should wait to take your medicines until after your blood is taken. Wear a short-sleeved or loose shirt on the day of the test. This will make it easier to draw your blood.

What do I need to know about the test results

Your healthcare provider will explain what your test results mean. The presence of ASO does not tell which disease you have now. It only tells if you have had a streptococcus infection that may have caused your illness. Several ASO tests may need to be done over a period of weeks.

Care Agreement

You have the right to help plan your care. To help with this plan, you must learn about your lab tests. You can then discuss the results with your healthcare providers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.