These are also muscle enzymes but the latter is less muscle specific than the former. AST has a longer half-life than CK. Because AST levels peak more slowly (24 to 48 hrs post insult) but do not revert to normal (in the absence of further insult) until 10-21 days, they are more useful in monitoring severity and the progress of recovery than CK. LDH can be fractionated into its isoenzymes. LD1 elevations can be seen in haemolysis and LD2 in cardiomyopathy.