27th May 2025

Aetiology

The most common cause is suppression of the HPA by exogenous steroid use, which may present clinically if steroids are rapidly weaned. Other causes of adrenal suppression include antipsychotics e.g. chlorpromazine and paraneoplastic steroid secretion.

Causes of SAI include:

• Congenital e.g. aplasia.
• Tumours e.g. adenomas, meningiomas, gliomas, craniopharyngiomas.
• Panhypopituitarism e.g. postpartum pituitary necrosis (aka Sheehan’s syndrome where hypovolaemic shock occurring in post-partum haemorrhage can cause pituitary infarction), pituitary apoplexy.
• Infection e.g. TB, meningitis, encephalitis, syphilis.
• Infiltration e.g. sarcoidosis, haemochromatosis, hypophysitis.
• Radiotherapy e.g. high-dose pituitary or whole-brain radiation.
• Surgery e.g. hypophysectomy.
• Trauma e.g. skull base fractures.
• Isolated ACTH deficiency.
• Corticotropin-releasing hormone (CRH) deficiency.