Adrenal insufficiency is classified into 2 types based on the level of impairment, primary adrenal insufficiency and secondary adrenal insufficiency. Secondary adrenal insufficiency may be further classified based on the causes into three types, such as hypopituitary causes, medication causes, and genetic causes.

Adrenal insufficiency is classified into 2 types based on the level of impairment.

Primary adrenal insufficiency

• Primary adrenal insufficiency is due to impairment of the adrenal gland, 80% due to an autoimmune disease called Addison’s disease or autoimmune adrenalitis. Also, the other cause includes autoimmune polyendocrine syndrome type 1 and type 2.

Secondary adrenal insufficiency

• Secondary adrenal insufficiency is caused by impairment of the pituitary gland or hypothalamus. The principal causes include pituitary adenoma (which can suppress production of adrenocorticotropic hormone (ACTH) and lead to adrenal deficiency unless the endogenous hormones are replaced); and Sheehan’s syndrome, which is associated with impairment of only the pituitary gland.
• Secondary adrenal insufficiency may be further classified based on the causes into three types:
  • Hypopituitary causes
  • Medication induced
  • Genetics