What is one of the lab tests used for diagnosing rheumatic fever?

One of the key laboratory tests used for diagnosing rheumatic fever is the ASO (Antistreptolysin O) titer. This test measures the level of antibodies produced in response to streptococcal infection, specifically to streptolysin O, a toxin produced by Streptococcus pyogenes, the bacteria responsible for strep throat. Following a streptococcal infection, an increased level of ASO indicates that the body is mounting an immune response to the bacteria, which is a crucial factor in diagnosing rheumatic fever, especially when there is a history of recent streptococcal pharyngitis.

While an ECG may be useful in evaluating cardiac involvement in rheumatic fever, it is not a diagnostic tool for the condition itself. Similarly, cholesterol levels and lipid panels are important for cardiovascular risk assessment but do not relate directly to the diagnosis of rheumatic fever. Therefore, the ASO titer stands out as the appropriate test for confirming the diagnosis of rheumatic fever due to its specificity in reflecting post-streptococcal immune response.