Adrenal insufficiency is defined by the impaired synthesis and release of adrenocortical hormones. It is classified based upon the mechanism:
●Primary adrenal insufficiency results from disease intrinsic to the adrenal cortex.
●Central adrenal insufficiency can be caused by impaired production or action of adrenocorticotropic hormone (ACTH). It can be caused by several mechanisms:
•Secondary adrenal insufficiency results from pituitary disease impairing release of adrenocorticotropic hormone (ACTH). In addition, unresponsiveness of end-organs to adrenocortical hormones is classified as secondary adrenal insufficiency, because this presents in a similar manner as diseases caused by adrenocorticotropic hormone (ACTH) deficiencies.
•Tertiary adrenal insufficiency results from the impaired release or effect of corticotropin releasing hormone (CRH) from the hypothalamus, which in turn impairs ACTH secretion.