27th May 2025

Aetiology

There are two groups of causes:

• ACTH-dependent disease: excessive ACTH secretion by the pituitary (known as Cushing’s disease) is the most common endogenous cause responsible for 70 – 80% of cases. Other causes include ectopic ACTH-secreting tumours (e.g. in small cell lung cancer) or excess ACTH administration.
• ACTH-independent disease: the most common cause overall is excess exogenous glucocorticoids. Other causes include adrenal adenomas, adrenal carcinomas and macronodular adrenal hyperplasia.