Which of these anti-stephtolysin O (ASO) test results is normal?

In assessing the normal range for anti-streptolysin O (ASO) titers, it is important to understand that these values are used primarily to evaluate whether a patient has had a recent streptococcal infection. Normal ASO levels generally fall within a specific reference range, which can vary slightly by laboratory but is typically considered to be less than 200 units/mL for most adults.

When looking at the provided option of 126, this value is below the threshold of 200, indicating that it falls within the normal range. A normal ASO titer suggests that there is no significant recent streptococcal infection, which is crucial for differential diagnosis of conditions such as rheumatic fever or post-streptococcal glomerulonephritis.

In contrast, values such as 156 and 200 are indicative of elevated ASO levels, suggesting either recent infection or that the patient has been exposed to streptococcal bacteria. The value of 100, while below the reference range, may not be widely accepted as a normal value depending on the cutoff defined by the laboratory standards being referenced.

Thus, a result of 126 is interpreted as normal because it is well below the conventional cutoff of