My cortisol in blood is 4.50 at 12:00 noon. Sodium is 137 and potassium is it normal? Or does it shows adrenal insufficiency?

No. When you check for adrenal insufficiency you need to do a Cortrysin stimulation test That test id done by taking a fasting cortisol then giving you an injection the testing the cortisol at 4pm then looking at the results somewhat complicated.