Do i have to fast before a liver function test and thyroid test?

Neither: You do not need to fast for the liver function tests. For the tsh, fasting is not generally needed, although there may be some variation in this tests between fasted and fed individuals. For more specialized tests (t3, t4, etc.), patients taking replacement treatment need to be aware of when they took the medication in relation to the test (it may be more elevated closer to the dose).

NO: These tests need not be done fasting, but when combined with the Cholesterol of a test for diabetes, they often are, as those tests do need to be fasting.