What is the Normal value of SGPT?

what is the normal value of SGPT in blood?
And if a person also Drink alcohol and have some doubt about heart disease, and if he goes for SGPT.
how doctor will reckon , either raise in SGPt level is due to heart disease or alcohol or liver?
Update: Thanks rehman bhae.
i was disoppointed first two days with not getting this question answeres.
but u resolve my difficulties.
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