Phaeochromocytoma

Pathophysiology

Adrenaline is produced by the “chromaffin cells” in the adrenal medulla of the adrenal glands. A phaeochromocytoma is a tumour of the chromaffin cells that secretes unregulated and excessive amounts of adrenaline. Adrenaline is a “catecholamine” hormone and neurotransmitter that stimulates the sympathetic nervous system and is responsible for the “fight or flight” response. In patients with a phaeochromocytoma the adrenaline tends to be secreted in bursts giving periods of worse symptoms followed by more settled periods.

25% are familial and associated with multiple endocrine neoplasia type 2 (MEN 2).

There is a 10% rule to describe the patterns of tumour:

  • 10% bilateral
  • 10% cancerous
  • 10% outside the adrenal gland

 

Diagnosis

  • 24 hour urine catecholamines
  • Plasma free metanephrines

Measuring serum catecholamines is unreliable as this will naturally fluctuate and it will be difficult to interpret the result. Measuring 24 hour urine catecholamines gives an idea of how much adrenaline is being secreted by the tumour over the 24 hour period.

Adrenaline has a short half life of only a few minutes in the blood, whereas metanephrines (a breakdown product of adrenaline) have a longer half life. This makes the level of metanephrines less prone to dramatic fluctuations and a more reliable diagnostic tool.

 

Presentation

Signs and symptoms tend to fluctuate with peaks and troughs relating to periods when the tumour is secreting adrenaline.

  • Anxiety
  • Sweating
  • Headache
  • Hypertension
  • Palpitations, tachycardia and paroxysmal atrial fibrillation

 

Management

  • Alpha blockers (i.e. phenoxybenzamine)
  • Beta blockers once established on alpha blockers
  • Adrenalectomy to remove tumour is the definitive management

Patients should have symptoms controlled medically prior to surgery to reduce the risk of the anaesthetic and surgery.

 

Last updated December 2018
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