Phaeochromocytoma

Question 1

What is phaeochromocytoma?

Answer 1

• Tumour of chromaffin cells in adrenal medulla > secrete excessive amounts of adrenaline

Question 2

What familial syndromes are associated with Phaeo?

Answer 2

• Multiple Endocrine Neoplasia Syndrome
• Neurofibromatosis
• Von Hippel - Lindau disease

Question 3

What are the sx of Phaeo?

Answer 3

• Headache
• Profuse sweating
• Palpitations
• Tremor
• Nausea
• Weakness
• Anxiety
• Sense of doom
• Epigastric pain
• Flank pain
• Constipation
• Weight loss

Question 4

What are the clinical signs of Phaeo?

Answer 4

• HTN, 50% paroxysmal
• Postural hypotension
• Tremor
• Hypertensive retinopathy
• Pallor
• Fever
• Reflex bradycardia if tumour release noradrenaline
• cafe au lait patches

Question 5

What Ix would you order for Phaeo?

Answer 5

• Bloods
  
  • Blood glucose - raised
  • Calcium +/- elevated.
  • Haemoglobin - elevated due to haemoconcentration from reduction in circulating volume
  • Plasma catecholamines and plasma metanephrines
• ​Urine
  
  • 24hr urine catecholamine, creatinine, metanephrine, vanillylmandelic acid (VMA)
• Imaging
  
  • CT CAP- first choice
  • MRI- to locate metastasis
  • MIBG labelled scan

Question 7

Metanephrine is a metabolite of adrenaline. Why measure it instead?

Answer 7

• Adrenaline has shorter half life and fluctuates throughout the day - unreliable

Question 8

What are the differentials for Phaeo?

Answer 8

• MEN syndrome - if bilateral tumours
• neurofibromatosis
• VHL disease
• Anxiety disorder
• carcinoid tumour
• Alcohol withdrawal
• Drug abuse

Question 9

How would you Mx Phaeo?

Answer 9

• Adrenelectomy - first line
• Before that, stabilize pt c medication
  
  • Short acting a-blocker - Phentolamine 2-5mg IV
  • Long acting a-blocker - Phenoxybenzamine 10mg/day
  • Beta blockers - propanolol

Question 10

What is the post-op care for adrenelectomy?

Answer 10

• 24hr urine metanephrine 2weeks post-op
• monitor BP

Question 11

Explain the Px of unopposed alpha stimulation after giving beta blockers?

Answer 11

1. stimulation of alpha-1 receptors results in smooth muscle contraction and vasoconstriction
2. Stimulation of beta-1 receptors increases heart rate, conduction, and contractility
3. stimulation of beta-2 receptors leads to smooth muscle relaxation
4. A balance between alpha-1 and beta-2 stimulation results in regulation of vascular tone
5. If a non-selective beta-blocker, such as propranolol, is used that has both beta-1 and beta-2 effects, this balance is disrupted in favor of alpha-1
6. vasoconstriction is favored