Troponin is a myocardial muscle protein that is released into the bloodstream when myocardial muscle is injured. Any elevation in Troponin T and I outside of normal range indicates cardiac necrosis. These proteins have a wide diagnostic timeframe, making them useful in diagnosing patients who did not immediately report symptoms. Myoglobin is the earliest marker of infarction, but it is found in cardiac and skeletal muscle. It is not as clinically useful as troponin. Sodium and potassium levels are not as immediately necessary when rapidly determining the cause of chest pain and course of treatment.