Hi Hazey
I had a test done for Cortisol, it was the ACTH test or short Synacthen test as it also known, does this sound like the one you are being asked to go on??
If it is it is nothing at all to worry about as far as my experience with it was concerned. It will test your Adrenal function. You will go in and have a baseline blood draw, then you will be injected with something to stimulate your Pituitary to release ACTH .
You will have to go back out and wait for another 15 mins then they will do a final blood draw to see how your Adrenal glands have responded .
Non of it painful or troublesome
Have you not been feeling very well?
Good luck hope you get sorted out