A nurse is reviewing the laboratory results of a child who was recently admitted for suspected rheumatic fever. The nurse should identify that which of the following laboratory tests can contribute to confirming this diagnosis? Select all that apply.

A. BUN is primarily used to assess kidney function. While it can be elevated in some inflammatory conditions, it's not a specific marker for rheumatic fever. B. PTT measures the time it takes for blood to clot. It's used to evaluate bleeding disorders, not inflammatory conditions like rheumatic fever. C. CRP is a sensitive marker of inflammation. It is often elevated in rheumatic fever due to the inflammatory response. D. ASO titer is a specific antibody against group A Streptococcus, the bacteria that often precedes rheumatic fever. Elevated ASO titers support the diagnosis. E. ESR is another non-specific marker of inflammation. It is often elevated in rheumatic fever.