Anti-Streptolysin O Antibody (ASO)
Fasting Required: No

Specimen: Blood

Results: 2-3 business days

Description: ASO is an antibody targeted against streptolysin O, a toxic enzyme produced by Group A streptococcus bacteria. Group A Streptococcus is responsible for diseases such as: Rheumatic fever, Scarlet fever and Strep throat.

A rise in ASO begins about one week after infection and peaks two to four weeks later. ASO levels do not rise with cutaneous infections. In the absence of complications or reinfection, the ASO level will fall to preinfection levels within 6 to 12 months. Over 80% of patients with acute rheumatic fever and 95% of patients with acute glomerulonephritis due to streptococci have elevated levels of ASO.

Methodology: Immunoturbidimetric

Limitations: False-positive ASO titers can be due to increased levels of serum beta-lipoprotein produced in liver disease and by "contamination" of serum by Bacillus cereus and Pseudomonas species. ASO is not sensitive for the diagnosis of streptococcal pyoderma.

Alternative Name(s): Streptolysin-O Antibody, Strep A, ASO, Streptococcus, Group A, Strep

Note: Result turnaround times are an estimate and are not guaranteed. Our reference lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.