Yes, an individual usually produces about 5 to 7 mgs of "prednisone" per day, naturally. When a patient has been on prednisone for more than a month, natural cortisol production is suppressed, and it may take months for the adrenal glands to produce high doses of cortisol and return to normal.
However, I'm not sure it's a case of not producing enough cortisol... I've always heard the theory is more that the immune system over-reacts and attacks inappropriately.
Diagnosed with ulcerative colitis spring 1999
Maintenance dose sulfasalazine
Probiotics, l-glutamine and fish oil caps