What are the tests to be done if sgpt is > 40?

Depends: Sgpt (aka alt) is a liver function test. Greater than 40 means above the normal range for that test. You will need to see your doctor, and possibly a gastrointestinal / liver specialist if there is a suspicion of liver disease / injury. Mildly elevated above 40 may be difficult to ascertain. Usually, the higher the number- the worse the liver injury.