ASO (anti-streptolysin O) analysis is a blood test used to measure the level of antibodies against streptolysin O, a toxin produced by the group A Streptococcus bacteria. The test is primarily used to diagnose a current or recent streptococcal infection, such as strep throat or rheumatic fever.
When the body is infected with streptococcal bacteria, the immune system produces antibodies to fight the infection. One of the antibodies produced is ASO, which is produced in response to streptolysin O. The level of ASO in the blood increases in response to the bacterial infection, and it takes a few weeks for the level to peak and then gradually decrease.
The ASO analysis involves drawing a blood sample from a vein in the arm. The blood sample is then sent to a laboratory for analysis. The normal range of ASO in the blood varies depending on the laboratory that performs the analysis, but it typically falls between 0-200 IU/mL.
An elevated level of ASO in the blood indicates that the body has recently been exposed to streptococcal bacteria. However, it does not necessarily mean that the person has an active infection, as the level of ASO can remain elevated for several weeks after the infection has resolved. Therefore, the ASO analysis is often used in conjunction with other tests, such as a throat culture, to confirm a streptococcal infection.
In addition to diagnosing streptococcal infections, the ASO analysis may also be used to monitor the effectiveness of treatment for the infection and to detect complications of the infection, such as rheumatic fever. The test may also be used to evaluate a person’s risk of developing rheumatic fever in the future.
In summary, the ASO analysis is a simple blood test used to diagnose recent or current streptococcal infections, such as strep throat or rheumatic fever. An elevated level of ASO in the blood indicates exposure to the bacteria, but it does not necessarily mean that the person has an active infection. The test is often used in combination with other diagnostic tests to confirm a streptococcal infection.
