Phaeochromocytoma

 

• Pathophysiology

  • Tumour, usually benign, of catecholamine-producing chromaffin cells of adrenal medulla.
  • Rule of 10s: 10% are extra-adrenal (e.g. carotid paraganglioma), 10% are malignant, 10% are familial, 10% are bilateral, 10% are in children.
  • Sympathetic nervous system stimulation includes β1 receptors in heart, leading to ↑HR, and α1 receptors in vascular smooth muscle, leading to vasoconstriction and hypertension.

• Signs and symptoms

  Episodes of PHAEochromocytoma:

  • Palpitations and ↑HR.
  • HeadAche.
  • Excess sweat (diaphoresis).

  Other symptoms:

  • Hypertension, which may be paroxysmal or sustained.
  • Hypertensive retinopathy.
  • Pallor
  • Diabetes, as catecholamines lead to ↑glycogenolysis and ↓insulin secretion.
  • Postural ↓BP.

• Risk factors

  • Middle age: mean onset age is 42.
  • Genetic: MEN2, Von Hippel-Lindau, NF1.

• DDx: Paroxysmal hypertension

  • Phaeochromocytoma
  • Drugs, especially cocaine.
  • Panic disorder.

• Investigations

  Catecholamine measurements:

  • Serum metadrenalines and normetadrenalines (catecholamine metabolites) are continually high so a reliable test, whereas serum catecholamines may be normal due to their episodic release.
  • 24h urine is a good test but can be a lot of hassle: shows raised catecholamines, metadrenalines, and normetadrenalines.

  Imaging:

  • MRI is best.
  • CT is acceptable but less sensitive.

• Management

  Initial treatment is ABySS:

  • Alpha-blocker: phenoxybenzamine. Should be done before β-blockade, as β-blockers alone may cause a hypertensive crisis via unopposed alpha stimulation.
  • Beta-blocker for HR.
  • Saline IV and ↑Salt diet to maintain intravascular volume while on α-blockers.

  Proceed to adrenalectomy if possible, or continue above medications.