Her initial diagnosis upon establishment into our clinic was Addison’s disease and hypothyroidism for which she was getting adequate treatment. Her clinical course had been complicated by multiple admissions for DKA, along with adrenal crises.
Following the adrenal crisis, her ACTH levels had been noted to be persistently elevated, at 3362, despite hydrocortisone replacement at optimal dosing and normal AM cortisol levels. Her hyperpigmentation continued to worsen. A 1mg dexamethasone suppression test failed to lower the ACTH levels.
Concern for a possible ectopic ACTH secretion prompted further investigation with imaging studies such as an abdominal Cat scan which showed no adrenal pathology. Pituitary MRI was ultimately performed which showed no evidence of pituitary lesions.
These were following by an 8mg Dexamethasone suppression test which adequately decreased the ACTH level. However re-check of ACTH levels, after weeks of being on her physiological hydrocortisone dosing, showed that her ACTH levels had started to rise again. Given she had also had multiple admissions for adrenal crises, the concern was raised for possible malabsorption.
Given her risk for auto-antibody development, there was concern for another autoimmune process such as Celiac disease, as a potential cause for malabsorption. Her TTG IgA antibodies were checked, however they were absent.
At this point, the decision was made to use prednisone as a means of suppression of ACTH, and she was given three days of 40mg Prednisone daily, followed by ACTH level testing, which showed a decrease from 2009 to 708. These results prompted us to change her hydrocortisone to prednisone daily dosing instead, and we converted her to a slightly higher dose of Prednisone.
In the setting of underlying DM, this may pose an additional challenge with glycemic control, but we plan for close clinic follow up and repeat ACTH levels a few weeks after she has been on the new prednisone regimen.
Conclusion: This is a rare case of a patient with polyglandular autoimmune syndrome, type 2, with a persistently elevated ACTH level, requiring Prednisone, instead of hydrocortisone for treatment of primary adrenal insufficiency in efforts to reduce ACTH levels.