Anistreptolysin o

This test measures the amount of antibody produced in
response to a recent streptococcal infection Streptolysin O
is a toxin made by the Group A streptococcus bacteria
(Streptococcus pyogenes). Antibodies made against this
foreign toxin are known as antistreptolysin O (ASO)
antibodies, which appear in the blood following infection
ASO test results can be reported in several different ways;
however, the interpretation is generally the same: the higher
the result is, the more antibody that is present in the blood
(unless a titer is performed, which is a ratio and therefore is
interpreted differently) .
The ASO antibody is either absent or present invery low
concentrations in patients who have not had a recent
streptococcal (strep) infection. Antibodies are produced
about a week to a month after the initial strep infection. ASO
levels peak at about 4 to 6 weeks after the illness and then
taper of but may remain at detectible levels for several
months after the strep infection has resolved