Originally Posted by culturism

Your doctor wants to assess if your body is capable of producing normal amounts cortisol when stimulated by ACTH. Synacthen is used as it is a synthetic drug mimics ACTH. If your body responds to synacthen then it would imply that your cortisol is low due to pituitary cause i.e it is not producing ACTH. If it does not respond as it should, then it would mean your adrenal glands have a problem.

Is the MRI for your adrenal gland / pituitary?

Post all your blood results