Epidemiology

Etiology

Pathophysiology

Clinical features

• ↑ Hematocrit
  • Steroids, particularly anabolic steroids, stimulate the production of erythropoietin

Diagnostics

• High-dose dexamethasone suppression test
  • Used to differ ectopic ACTH secretion vs Cushing disease
  • This test is similar to the low-dose dexamethasone suppression test but uses 8 mg of dexamethasone. Most pituitary adenomas retain partial sensitivity to feedback inhibition in response to high doses of glucocorticoids, while ectopic tumors are resistant even to high doses.

Treatment

Bilateral adrenalectomy

• Indications
  • Primary hypercortisolism caused by bilateral adrenal disease (recommended curative treatment)
  • Emergency treatment in severe ACTH-dependent hypercortisolism that cannot be controlled pharmacologically
  • Symptomatic treatment for metastatic or occult ectopic tumors
• Complication: Nelson syndrome (post adrenalectomy syndrome)
  • Etiology: bilateral adrenalectomy in patients with a previously undetected pituitary adenoma
  • Pathophysiology: bilateral adrenalectomy → no endogenous cortisol production → no negative feedback from cortisol on the hypothalamus → ↑ CRH production → uncontrolled enlargement of preexisting but undetected ACTH-secreting pituitary adenoma → ↑ secretion of ACTH and MSH → manifestation of symptoms due to pituitary adenoma and ↑ MSH
  • Clinical features: headache, bitemporal hemianopia (mass effect), cutaneous hyperpigmentation
  • Diagnostics
    • High levels of β-MSH and ACTH
    • Pituitary adenoma on MRI confirms the diagnosis.
  • Treatment: surgery (e.g., transsphenoidal resection) and/or pituitary radiation therapy (e.g., if the tumor cannot be fully resected)