Makindo Medical Notes.com

Related Subjects: |Adrenal Physiology |Addisons Disease |Phaeochromocytoma |Adrenal Adenomas |Adrenal Cancer |Cushing Syndrome |Cushing Disease |Congenital Adrenal hyperplasia |Primary hyperaldosteronism (Conn's syndrome) |ACTH |McCune Albright syndrome

Hypertension in phaeochromocytoma is best treated with Phenoxybenzamine a nonselective alpha blocker

About

• Uncommon cause of secondary hypertension
• Important to know perioperative management
• Tumours of chromaffin cells of the sympathetic nervous system

Aetiology

• Tumour of the chromaffin cells within the adrenal medulla and sympathetic chain
• Secretes catecholamines - Adrenaline [US Epinephrine] , Noradrenaline [US Norepinephrine] and dopamine
• Rarely produces opioids, endothelin, erythropoietin, neuropeptide Y
• Seen in 1-2 out of every 1000 hypertensive patients
• Commoner on the right then left and may not be in adrenal - bladder, thorax

We call it the 10 x 10 tumour

• 10% are malignant, 10% lie outside the adrenals
• 10% are familial, 10% in children
• 10% Bilateral, 10% calcify
• 10% recur after removal
• 10% in bladder [famous hypertensive crisis with urination]
• 10% in thorax. Usually less than 10 cm in size

Pathology

• Grey tumour which may be extra-adrenal

Associations

• Von Hippel-Lindau syndrome
• Neurofibromatosis Type 1
• MEN Type 2a and 2b

Clinical

• Hypertension which may be intermittent, Headaches, sweating and tachycardia
• Feeling of doom, Nausea, tremor
• Symptoms can be paroxysmal
• Weight loss, Hyperglycaemia
• Hypotension - postural and related to surgery
• Arrhythmias, Worsening Angina/IHD

Investigations

• Check FBC and U&E and Calcium (especially if MEN suspected)
• 24-hour urinary catecholamines/urinary metanephrines should be measured and is 98% sensitive
• CT or MRI best identify tumour once biochemical evidence. Risk of finding incidentalomas
• MIBG scan can complement CT/MRI but less commonly done now
• Clonidine suppression test - clonidine reduces catecholamines in the normal subject but not with phaeochromocytoma
• Fine needle aspiration is contraindicated

Management

• Hypertension management: Start with alpha blockade
  • Doxazosin 2-32 mg OD PO
  • Phenoxybenzamine 10 mg/12h PO
  • Phentolamine 2-5 mg IV is short acting
• Beta blockade comes after alpha blockade
  • Consider if tachycardia or arrhythmias or ACS
• Surgery may lead to the release of stores of catecholamines with an acute hypertensive crisis. May be done laparoscopically. Sudden removal of catecholamines can lead to sudden hypotension needing volume expansion. Great care must be taken with preparation for surgery with an experienced anaesthetist.
• First the patient is alpha blocked with Phenoxybenzamine 10mg/24h often several weeks preoperatively. The dose can be up titrated. An alternative is Doxazosin. Later if needed Beta blockade with for example Propranolol other agent can be started.
• Blood pressure can fall precipitously as soon as the tumour is removed and the patient may need immediate volume replacement. Requires excellent surgical and anaesthetic control.
• Survival is good if there is the complete removal of the tumour

Complications

• Dilated cardiomyopathy
• Atrial fibrillation /SVT
• Ventricular Tachycardia / fibrillation
• Diabetes mellitus
• Stroke
• Hypertensive encephalopathy