The normal range of ASO titer levels can vary depending on the laboratory and the specific test method used. In general, an ASO titer of less than 200 IU/mL is considered normal for adults. However, it's important to note that elevated ASO titers can be a sign of an underlying infection, such as strep throat or scarlet fever, and should be interpreted in the context of a person's overall health and symptoms. If you have any concerns about your ASO titer level or have experienced symptoms such as sore throat, fever, or rash, it's important to see a healthcare professional for evaluation and proper diagnosis.