Does the long term use of steroids cause atrophying of the adrenal medulla?

The adrenal cortex and the adrenal medulla perform very different functions, and they are affected by different physiological conditions. The adrenal cortex is responsible for producing a class of hormones called glucocorticoids, such as cortisol and corticosterone. As the name implies, the most essential function of the glucocorticoids is to regulate the concentration of glucose in the bloodstream. The production and release of glucocorticoids from the adrenal cortex is tightly regulated by feedback mechanisms...

The adrenal cortex and the adrenal medulla perform very different functions, and they are affected by different physiological conditions. The adrenal cortex is responsible for producing a class of hormones called glucocorticoids, such as cortisol and corticosterone. As the name implies, the most essential function of the glucocorticoids is to regulate the concentration of glucose in the bloodstream. The production and release of glucocorticoids from the adrenal cortex is tightly regulated by feedback mechanisms that are sensitive both to fluctuations in glucose concentrations and to changes in the concentration of glucocorticoids in the bloodstream. So, for example, when glucose concentrations fall, the anterior pituitary gland releases ACTH, a hormone that stimulates the production of glucocorticoids in the adrenal cortex; the increase in glucocorticoids serves to increase blood glucose levels through a variety of pathways. When glucose and glucocorticoid levels rise too high, the pituitary responds by decreasing its secretion of ACTH, thus bringing the system back into balance.

However, the long-term use of supplemental corticosteroids can cause a persistent elevation in blood levels of both glucocorticoid hormones and glucose, a condition which does not respond to the pituitary's compensatory efforts. In the short term, ACTH levels may fall very low as the pituitary attempts to compensate for the over-abundance of corticosteroids in the bloodstream; in the longer term, the consequence of this persistent depression of ACTH is that the adrenal cortex receives insufficient stimulation to maintain its ordinary structure and functioning, resulting in the atrophy of its tissues. A similar phenomenon is often observed with any hormone-replacement regimen.

How does the adrenal medulla fit into this picture? Well, the adrenal medulla does NOT participate in the production of glucocorticoids, so it is far less likely to be adversely affected by the use of corticosteroids. Its primary job is to produce shorter-acting stimulatory hormones and neurotransmitters such as epinephrine, norepinephrine, and dopamine; these systems are affected only tangentially by the corticosteroid/ACTH feedback loop, so it is unlikely that the use of corticosteroids would cause any significant atrophy of the adrenal medulla.