Antistreptolysin O (ASO) titer is a blood test to measure antibodies against
streptolysin O, a substance produced by group A streptococcus bacteria.
Antibodies are proteins our bodies produce when they detect harmful substances,
such as bacteria.
How the Test is Performed
How to Prepare for the Test
DO NOT eat for 6 hours
before the test.
How the Test will Feel
When the needle is
inserted to draw blood, you may feel moderate pain, or only a prick. After the
test, you may have some throbbing at the site.
Antistreptolysin O titer
Why the Test is Performed
You will need the test
if you have symptoms of a previous infection by group A streptococcus. Some
illnesses caused by this bacteria are:
·
Bacterial endocarditis, an infection of the inner lining of your
heart
·
Strep throat
Normal Results
A negative test result
means that you do not have strep infection. Your health care provider may do
the test again in 2 to 4 weeks. At times, a test that was negative the first
time may be positive (meaning it finds ASO antibodies) when done again.
Normal value ranges
may vary slightly. Talk to your provider about the meaning of your test
results.
What Abnormal Results Mean
An abnormal or
positive test result means you recently had a strep infection, even if you had
no symptoms.ml
Risks
Veins and arteries
vary in size from person to person, and from one side of the body to the other.
Because of this, it may be harder to get a blood sample from some people than
it is from others.
Other risks associated
with having blood drawn are slight, but may include:
·
Excessive bleeding where the needle is inserted
·
Fainting or feeling lightheaded
·
Hematoma (blood buildup under the skin)
·
Infection (a slight risk any time the skin is broken)
Alternative Names
ASO titer; ASLO
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