Antistreptolysin O titre (ASOT) - serum

Last updated: Saturday, 16, June, 2007

MBS Online Search Page: Click here for details

Item Process
Specimen

5-10 mL blood in plain tube.

Method

Inhibition of streptolysin-induced red cell lysis.

Reference Interval

Age dependent.

In adults, typically <166 Todd units, but consult pathologist.

Application

To confirm exposure to Streptococcus pyogenes, in the investigation of rheumatic fever and acute glomerulonephritis.

Indicated occasionally in the investigation of severe cellulitis and rarely in recurrent tonsillitis.

Interpretation

A high titre, or a two fold rise in titre, indicates recent infection. Antibodies are not detected until at least 3 weeks post infection.

See also Antideoxyribonuclease B (AntiDNase B) antibodies - serum.

Reference

Martin DR. In: Stevens DL and Kaplan EL. Streptococcal Infections. Oxford University Press 2000.