Cushing's syndrome - adrenal causes

Cushing's syndrome is caused by long-term exposure to excess cortisol. It can come from the pituitary (Cushing's disease), from an ectopic source, or from the adrenal gland itself. This page covers the adrenal causes, which are managed by adrenalectomy rather than pituitary surgery.

How it presents

Overt Cushing's causes weight gain around the trunk, easy bruising, purple striae, muscle weakness, osteoporosis, diabetes and high blood pressure. Subclinical or autonomous cortisol secretion is often much more subtle - diabetes, hypertension and fractures that would otherwise seem age-related - and is increasingly picked up during workup of an incidentaloma.

How it is diagnosed

  • Overnight 1 mg dexamethasone suppression test. Failure to suppress cortisol is the screening trigger.
  • 24-hour urinary free cortisol and/or late-night salivary cortisol as complementary tests.
  • ACTH measurement to separate adrenal (ACTH-suppressed) from pituitary or ectopic (ACTH-normal or elevated) causes.
  • Adrenal imaging (CT or MRI) to localise the source when ACTH is suppressed.

When surgery is considered

Surgery is offered when an adrenal cortisol-producing adenoma is confirmed or strongly suspected, and the cortisol excess is either overt or, in subclinical cases, contributing to cardiovascular or metabolic disease. Cardiovascular risk factors (blood pressure, glucose, lipids) have been shown to improve after adrenalectomy in patients with autonomous cortisol secretion.7

How the operation is done

Minimally invasive unilateral adrenalectomy is the standard operation. See robotic adrenalectomy. Because the other gland has been suppressed by long-standing cortisol excess, steroid cover is given around the operation and tapered slowly afterwards while the remaining gland recovers. This may take many months.

After surgery

Patients often notice improvement in blood pressure, blood sugar and energy. Steroid replacement is continued until the opposite adrenal gland shows recovery on morning cortisol testing; this is coordinated with your endocrinologist.7

Cushing's surgery should be planned jointly with an endocrinologist so that steroid cover and follow-up are smooth. Use contact or second opinion to discuss.

Considering adrenal surgery?

You can request a second opinion on imaging, hormone testing and treatment options before you decide.