@chpfireball

Would it be possible to have your morning cortisol level checked while you are still on 1 mg of prednisone? Checking a cortisol level might be useful to help decide if Prednisone can be stopped. Any amount of Prednisone might interfere with your cortisol level but the lab test might still be useful. My endocrinologist said I would need to be on 3 mg or less of Prednisone before she would check my adrenal function.

Being extremely exhausted with normal amounts of physical exertion might be a symptom of adrenal insufficiency. If your cortisol level is low, you are also more likely to have a flare of your autoimmune condition.

A very low morning cortisol level (< 5 mcg/dL or < 150 nmol/L, depending on the lab assay) strongly suggests ongoing adrenal insufficiency and the need to continue a physiological dose (3-5 mg) of Prednisone.