Secondary Adrenal Insufficiency

• Secondary adrenal insufficiency results from inadequate adrenocorticotropic hormone (ACTH) and a lack of stimulation of the adrenal glands, leading to low cortisol. This is the result of loss or damage to the pituitary gland. Secondary adrenal insufficiency can be due to:

  • Tumours (e.g., pituitary adenomas)
  • Surgery to the pituitary
  • Radiotherapy
  • Sheehan’s syndrome (where major post-partum haemorrhage causes avascular necrosis of the pituitary gland)
  • Trauma
• • Secondary adrenal insufficiency occurs when pituitary ACTH production is insufficient; this leads to reduced cortisol production and adrenal atrophy. Causes include intracranial disorders, such as pituitary tumours, subarachnoid haemorrhage, and traumatic brain injury.
• Confirming diagnosis of Secondary adrenal insufficiency:

  • ACTH levels - low
  • Plasma renin - normal
  • Aldosteron - normal
• Secondary adrenal (and tertiary) insufficiency causes glucocorticoid but not mineralocorticoid deficiency. This is because aldosterone is regulated primarily by the renin-angiotensin system which is independent of the hypothalamus and pituitary gland.