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Diagnostic Tests 2023

ASLO exam: what é, what it is for and how é done

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ASLO exam: what é, what it is for and how é done
ASLO exam: what é, what it is for and how é done

The ASLO test, also called ASO, AEO or anti-streptolysin O, aims to identify the presence of a toxin released by the bacterium Streptococcus pyogenes, streptolysin O, which is normally associated with cases of pharyngitis or rheumatic fever and glomerulonephritis, in the most severe cases.

The result of antistreptolysin O can be altered 1 to 3 weeks after infection with the bacteria, so it is one of the main tests for the diagnosis of Streptococcus pyogenes infection, especially when there is frequent and lasting sore throat to be resolved. Learn more about Streptococcus pyogenes.

When this bacteria is not identified and treated correctly, there is the possibility of developing complications and symptoms such as shortness of breath, chest pain or pain and swelling in the joints, for example, it is essential to consult the general practitioner or infectious disease specialist. to initiate the most appropriate treatment.


What is it for

The ASLO test is used to identify the presence of a toxin produced by the bacterium Streptococcus pyogenes and, therefore, is usually indicated when the person has recurrent symptoms of pharyngitis, such as redness and swelling in the throat, difficulty in swallowing, general he alth and fever, for example, so that it is possible to identify whether this bacterium is related to pharyngeal inflammation.

In addition, this test may be requested when the person has high levels of antistreptolysin O even without symptoms of pharyngitis, as it may indicate that the bacteria has managed to spread through the blood and reach other organs, with increased risk of developing glomerulonephritis, scarlet fever, or rheumatic fever, for example, where the person may also experience shortness of breath, joint pain and swelling, and red patches on the skin. Learn how to identify rheumatic fever.

How it's done

The ASLO test must be performed after a fasting period of 4 to 8 hours, as recommended by the doctor or laboratory, and is performed from the collection of a blood sample that is sent to the laboratory for analysis. It is important to indicate, at the time of the examination, if you are using any medication, such as antibiotics, corticosteroids or immunosuppressants, as they may interfere with the test result.

In some cases, when there are symptoms involving the throat, the doctor may also recommend collecting a sample from the throat to identify the infectious agent responsible for the symptom.

If Streptococcus pyogenes infection is confirmed, an antibiogram is performed to verify the most appropriate antibiotic for the treatment. Understand how the antibiogram is made.

What does the result mean

The normal values of antistreptolysin O may vary according to the laboratory and age, however, in general it is considered normal:

  • Adults: up to 200 IU/mL;
  • Children: up to 150 IU/mL.

In the case of a positive result, that is, when an amount of antistreptolysin O is identified above what is considered normal, the doctor usually requests a repeat test after 10 to 15 days to verify that the levels of this antibody in the blood are constant or decrease over time, checking whether the infection is active or not.

ASLO positive

Although positive results are characteristic of Streptococcus pyogenes infection, not all people develop symptoms of rheumatic fever, glomerulonephritis or tonsillitis, for example, however, they should be accompanied by a doctor, performing periodic blood tests and check-ups. up heart. See which exams are requested to evaluate the heart.

In addition, some situations can lead to an increase in this antibody without necessarily being related to the bacterium Streptococcus pyogenes, such as viral hepatitis, tuberculosis and contamination of the sample, being recommended to perform other tests to confirm the diagnosis.

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