Anti-streptolysin O titer
Key points
- This is a blood test to measure anti-streptolysin O (ASO) antibodies.
- Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand.
- Interfering factors such as high levels of beta lipoproteins can affect the test results.
- The preparation you can provide for this test depends on your child's age and previous experiences.
Alternative names
ASO titer
Definition
This is a blood test to measure anti-streptolysin O (ASO) antibodies.
How the test is performed
Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
The blood is then sent to the laboratory for analysis.
How to prepare for the test
Fast for 6 hours before the test. Interfering factors such as high levels of beta lipoproteins can affect the test results.
For infants and children:
The preparation you can provide for this test depends on your child's age and previous experiences. For specific information regarding how you can prepare your child, see the following topics:
- Infant test or procedure preparation (birth to 1 year)
- Toddler test or procedure preparation (1 to 3 years)
- Preschooler test or procedure preparation (3 to 6 years)
- School age test or procedure preparation (6 to 12 years)
- Adolescent test or procedure preparation (12 to 18 years)
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is used to detect prior infection by Group A Streptococcus, the bacterium responsible for diseases such as glomerulonephritis, rheumatic fever, bacterial endocarditis, and scarlet fever.
Written and revised by
David Cohen, M.D.
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