Synonyms: ASO titre, ASLO
Related tests: full blood count, throat swab
Clinical significance
It shows the extent of the immune response to group A beta-haemolytic streptococcus (the causative agent of acute rheumatic fever and scarlet fever); the titre becomes positive 7-10 days after infection, peaks at about one month and then declines over a period that may last up to a year. The titre does not give protection and rises with each new contact with the organism. Antibiotic treatment does not bring the titre back to normal quickly.
Clinical indications
Suspected group A beta-haemolytic streptococcus infection.
Sample type
The patient must have a blood sample taken.
Preparation
You must fast for at least 8 hours; a small amount of water is allowed. You must have been standing or sitting upright for at least 30 minutes.