A nurse is reviewing the laboratory findings of a client who experienced an acute myocardial infarction 6 days ago. Which of the following laboratory values should the nurse expect to remain elevated at this time?

A. Troponin is the most sensitive and specific marker of myocardial damage. It begins to rise within 3–6 hr after an MI, peaks at 10–24 hr, and can remain elevated for 10–14 days, so it would still be elevated 6 days later. B. Creatinine phosphokinase (CPK): Peaks in 24 hr and returns to baseline within 2–3 days. C. Creatinine kinase-MB (CK-MB): Peaks in 24 hr and returns to normal in 2–3 days, making it useful for detecting reinfarction but not late detection. D. Myoglobin: Rises quickly (within 1–2 hr) but returns to normal within 24 hr, so it would no longer be elevated at 6 days.