Streptolysin O Titre

Alternative name: ASO, ASO Ab
Description: Antistreptolysin O antibodies will be raised after infection with streptococci. Measurement can be useful diagnostically if recent streptococcal infection is thought to be important in aetiology. Diseases include: rheumatic fever, scarlet fever and post streptococcal glomerulonephritis where C3 and C4 levels should also be measured). Assay is complicated by wide range of levels found in individuals with past infection (often minor, largely undetected infection). Levels rise in general population during epidemics.
Indication: Any condition associated with infection by streptoccocus pyogenes e.g. rheumatic fever, nephritis, arthritis etc.
Interpretation: A rise in ASO titre above 200 U/mL may be associated with recent strep infection though the “normal” range is rather broad. Individuals with levels up to 400U/ml may be unsymptomatic.
Sample: Serum Separator Tube (SST)
Assay details: Nephelometry
Restrictions: Increased levels of lipids (lipaemia), haemoglobin (haemiolysis), or the prescence of icterus in the assay sample may affect the assay result.
Reference range: <200IU/mL
Assay range Notes: 200-400IU/mL High normal range
Assay range 0-5000 IU/ml
Turnaround time: 5 – 7 days
Analysing laboratory: Immunology The James Cook University Hospital