I stopped taking Abiraterone three months ago to have a vacation. Was on it for six years. I tapered of the prednisone. I became very fatigued. Could hardly do anything in the morning and then limited things in the afternoon. then I thought of my low cortisol level (due to the abi) a couple years ago. My doc said to up the pred to 10mg/day. that did the trick. I started back on the pred a few days ago and feel much better. I had a talk with a hematologist and he said I had Addison's disease. this is a very serious condition. I was on abi for so long, my adrenals have stopped producing cortisol. I will be on pred the rest of my life.
If any of you have a problem like this, don't ignore it and think it will get better on its own.
One question I forgot to ask was are the adrenals incapable of producing testosterone as well? I will ask to be sure. EDIT: I asked and the testosterone is not affected by Addison's.
One more wonderful thing. I have elevated AST. Like 188. He says I have a virus in the liver and it will clear up in three to six months on its own. This can also cause fatigue. Oh joy! Lose , lose. At least he says, in his opinion, I don't have mets there. Will bring that up with my MO.