What effect does long-term corticosteroid use have on adrenal function?

Long-term corticosteroid use can lead to adrenal insufficiency due to a mechanism known as feedback inhibition. When exogenous corticosteroids are administered for an extended period, they raise the levels of circulating glucocorticoids in the body. The hypothalamus and pituitary gland sense these elevated levels and, in response, reduce the production of adrenocorticotropic hormone (ACTH). Since ACTH stimulates the adrenal glands to produce cortisol, decreased ACTH levels can lead to decreased adrenal activity over time.

As a result, the adrenal glands may shrink (a condition known as adrenal atrophy) and become less capable of producing cortisol independently. If corticosteroid treatment is suddenly discontinued, or if circulation of corticosteroid levels falls, the adrenal glands may not respond adequately due to their reduced functional capacity, resulting in adrenal insufficiency. This highlighting the importance of gradual withdrawal from corticosteroid therapy to allow the adrenal glands time to resume normal function.