Antistreptolysin O (ASO)
Antistreptolysin O (ASO) measures antibodies against streptolysin O, a toxin produced by Group A Streptococcus. Elevated levels indicate recent or past streptococcal infection.
Category: Infectious Disease
Also known as: antistreptolysin o ab
Reference range: 0–200 IU/mL (Source: ABIM)
Standard unit: IU/mL
High values may indicate
Elevated ASO titers indicate a recent Group A streptococcal infection and may be associated with post-streptococcal sequelae such as rheumatic fever or post-streptococcal glomerulonephritis.
Low values may indicate
Normal or low ASO levels. No evidence of significant recent streptococcal infection.
Frequently asked questions
- What is a normal Antistreptolysin O (ASO) level?
- A typical reference range for Antistreptolysin O (ASO) is 0–200 IU/mL (source: ABIM). Reference ranges vary by laboratory, age, and sex, so always compare against the range on your own lab report.
- What units is Antistreptolysin O (ASO) measured in?
- Antistreptolysin O (ASO) is most commonly reported in IU/mL. Labs in different countries may use other units — you can convert between them with BloodId's blood test unit converter.
- Where do Antistreptolysin O (ASO) reference ranges come from?
- BloodId uses ABIM standard reference ranges and educational information from MedlinePlus (see our methodology). Reference ranges still vary by lab, age, and sex, so always compare against your own report.
- Can I track Antistreptolysin O (ASO) over time?
- Yes. Upload results from any lab and BloodId charts your Antistreptolysin O (ASO) over time against its reference range, so you can see whether the trend is rising, falling, or stable.
Related biomarkers
Source: BloodId admin-reviewed
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