Secondary/Tertiary Adrenal Insufficiency

Secondary: lack of production of ACTH by the pituitary gland
Tertiary: lack of CRH secretion by the hypothalamus

Aetiology

  • Iatrogenic (excess exogenous steroid) - inhibit CRH production and ACTH production, adrenal gland becomes atrophied and is unable to produce cortisol even acutely when ACTH is given endogenously
  • Pituitary/hypothalamic disorders - tumours, surgery and radiotherapy

Clinical presentation

Similar to Addison's except:
  • Skin pale (no ↑ ACTH)
  • Aldosterone production intact (regulated by RAAS)
    • No hypertension

Investigations

  • Insulin tolerance test
  • CRH stimulation test
  • MRI

Management

  • Treat with hydrocortisone replacement (fludrocortisone unnecessary)