What is Adrenal Insufficiency?
Adrenal insufficiency can be divided into primary, secondary and tertiary.
- Primary adrenal insufficiency (Addison's disease) results from damage to or dysfunction of the adrenal gland itself.
- Secondary adrenal insufficiency results from inadequate pituitary ACTH secretion and therefore inadequate cortisol release.
- Tertiary adrenal insufficiency results from inadequate CRH release from the pituitary and the resultant decrease in ACTH release.
Diagram of the classification of adrenal insufficiency - click to enlarge
Primary adrenal insufficiency is clinically distinct from secondary and tertiary insufficiency. In primary insufficiency there is a decrease in both mineralocorticoids (aldosterone) and glucocorticoids (cortisol), whereas in secondary and tertiary insufficiency the aldosterone levels are virtually normal as the zona glomerulosa is largely independent of ACTH.
