This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Antistreptococcal antibody titres (ASOT)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Antistreptolysin O antibodies will be raised after infection with streptococci. Levels greater than 200 units per millilitre are considered significant (although cut off levels will vary between laboratory undertaking the test).

Measurement can be useful diagnostically if recent infection with streptococci is known to be important in aetiology. Diseases include:

  • rheumatic fever
  • post streptococcal glomerulonephritis
  • scarlet fever
  • erysipelas

The antibody level appears as early as one week following streptococcal infection. The titre level rises rapidly by 3-4 weeks and then declines quickly; the antibody level may remain raised for months.

Note that even in severe streptococcal infection there will be an elevated ASOT titre in only 70-80% of patients.

False positive results are associated with tuberculosis, liver disease (e.g. active viral hepatitis) and bacterial contamination.

If the specimen is lipaemic or contaminated then the latex agglutination method may result in a false positive result.

If required then other streptococcal antigens may be tested e.g. antistreptococcal hyaluronidase and antideoxyribonuclease.


Related pages

Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page

The content herein is provided for informational purposes and does not replace the need to apply professional clinical judgement when diagnosing or treating any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions.


Copyright 2024 Oxbridge Solutions Limited, a subsidiary of OmniaMed Communications Limited. All rights reserved. Any distribution or duplication of the information contained herein is strictly prohibited. Oxbridge Solutions receives funding from advertising but maintains editorial independence.