Alternate Names : Anti-Streptolysin O
This test detects an antibody known as ASO, or anti-streptolysin O. This antibody appears when a person has certain bacteria in the blood. The bacteria are Group A streptococcus, which make an enzyme called streptolysin O. This enzyme destroys red blood cells.
Who is a candidate for the test?
This test can be used to:
confirm a recent or ongoing infection with Group A streptococcus
help diagnose rheumatic fever or a streptococcal infection in the kidneys
determine whether a person has rheumatoid arthritis or rheumatic fever
How is the test performed?
To do the test, a blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or tourniquet, is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A fine needle is gently inserted into the vein chosen and the tourniquet is removed. Blood flows from the vein through the needle. It is collected in a syringe or vial for testing in the laboratory. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.