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is an acute phase reactant.
It indicates there is a problem / gives a rough idea of its severity / helpful in follow up...
It does not say what the actual problem is...
Your father's level is very high.
Infection is a very common cause.
It has to be repeated in a few days.
If it does not come down, extensive investigations will be necessary to elucidate the cause.
It is long and tedious at times, and only the physician following him can decide better - based on repeated examination and the results of the tests at each step.
Wishing speedy recovery