what cardiac enzyme is the first to rise in myocardial infarction?!
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Actually the first cardiac marker to elevate after an MI is Myoglobin. It elevates immediately with the onset of an MI. It also decreases back to normal within 4 to 6 hours. Creatine Kinase (CK) elevates 4 to 8 hours post MI and the MB fraction elevates at very closely the same rate. Troponin also elevates at about the same time. Lactate dehydrogenase (LD) generally elevates with 24 - 36 hours post MI. With LD we look at the isoenzymes, there are five, normally fraction 2 is a higher percentage than fraction one but in an MI the percentages reverse. LD isoenzymes can only be determined by electrophoeresis, at one time the same was true for CK isoenzymes. With the advent of chemical means to dermine CKMB and the development of the test for troponin, LD and LD isoenzmes have fallen out of use for MI though they are still useful in diagnosing liver and kidney problems.
Other Answers:
CK MB (4 hours) then troponins (6 hours) and lastly LDH (24 hours)
cpk-mb
troponin
ldh
I'm a cardiologist. Myoglobin does rise first, but it is way too sensitive, in my experience, and is often positive falsely. Troponin rises next. CPK is the third to rise. And LDH rises several days later.
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