I’ve had PMR for 2.5 years now. Every time I get down to about 3 or 4mg of steroid I have a problem with my cortisol levels. Mine too are low normal. The fatigue is overwhelming and does not just go away after a few days. I had to go back up to 6mg. Just because we are down on the steroids or off them completely does not mean the body is ready to jump back in action. Cortisol is a hormone produced by the adrenal glands that plays a vital role in regulating various bodily functions, including immune response. It gets smashed by the steroid and takes awhile to get going again. I’m seeing an endocrinologist the end of this month to help me with this issue. So frustrating.