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Phaeochromocytoma

Indications for Screening

  1. patients with hypertension and paroxysmal symptoms
  2. patients with hypertension which is resistant to conventional treatment
  3. patients <35 years old with hypertension
  4. patients developing a hypertensive crisis during general anaesthesia/surgery
  5. patients with a positive family history for phaeochromocytoma, MEN II, VHL or neurofibromatosis.
  6. patients with unexplained heart failure
Since phaeochromocytoma is potentially lethal, a high index of suspicion is required and the threshold for screening should be low.

Clinical Features

Hypertension Sustained or episodic, often resistant to conventional therapy
'Crises' Paroxysmal attacks develop in 50% of patients.

Symptoms during 'crisis' - palpitations, sweating, feeling of impending doom, breathlessness and headaches. These attacks may last minutes to hours and usually occur spontaneously. They may be precipitated by exercise, straining, certain drugs , abdominal palpation or surgery.
Neurological Headache, paraesthesia, visual disturbances
Cardiovascular Palpitations, chest pain, dyspnoea, postural hypotension
Gastrointestinal Abdominal pain, constipation, nausea

Investigations

A: Demonstrate Catecholamine Hypersecretion
24 hour urine collection for catecholamines Collections should be in acid containers and be tested for free catecholamines. At least two 24 hour urine samples should be tested.

Please note tricyclic antidepressants and Labetalol should be stopped 4-7 days prior to diagnostic evaluation. There are no dietary restrictions during the investigation period.

Please refer to Endocrine clinic if catecholamine hypersecretion is confirmed.



B: Tumour Localisation
Magnetic resonance imaging (MRI) of the abdomen 90% of phaeochromocytomas are found in the adrenal gland and 98% are found in the abdomen. MRI is highly sensitive at localising these tumours, with a pick-up rate approaching 100%.
123I-MIBG scan
(meta-iodobenzylguanidine) 		It is useful for looking for multiple tumours and metastases. However, its sensitivity is only 70%.