The involvement of ACTH and cortisol in the hypothalamic-pituitary-adrenal axis.
Cortisol produced in the adrenals or by an adrenal tumour has a negative feedback effect on ACTH production. Oral steroids have the same effect. Conversely, ACTH stimulates cortisol production and secretion, as do pituitary or ectopic tumours and intramuscular injections of ACTH.
