Phaeochromocytoma Flashcards
What type of tumour is a phaeochromocytoma?
A catecholamine-secreting tumour derived from chromaffin cells of the adrenal medulla
What percentage of phaeochromocytomas are extra-adrenal, and what are they called?
10% (up to 30%) are extra-adrenal and are called paragangliomas
Where are paragangliomas typically found?
In the sympathetic chain
= commonly in the
1. head
2. neck
3. thorax
4. pelvis
5. bladder
What is the classical triad of symptoms in phaeochromocytoma?
- Hypertension (episodic)
- Headache
- Sweating
What triggers phaeochromocytoma episodes?
Stress, exercise, posture changes, tumour palpation
How does a bladder paraganglioma present?
Episodes are triggered by micturition (urination)
What are the main cardiovascular signs of phaeochromocytoma?
- Hypertension (paroxysmal or persistent)
- Postural hypotension
- Tachycardia or paradoxical bradycardia
What is the first-line biochemical test for phaeochromocytoma?
Plasma free metanephrines
Why are metanephrines tested instead of catecholamines?
Metanephrines are the breakdown products of catecholamines, and their levels are more stable and reliable
What is the first-line preoperative management for phaeochromocytoma?
Full α-blockade (e.g. phenoxybenzamine, doxazosin)
When is β-blockade given?
Only after full α-blockade, and only if needed for tachycardia or palpitations
Why should patients have a high-salt diet before surgery?
To prevent postural hypotension caused by α-blockade
What is the definitive treatment for phaeochromocytoma?
Laparoscopic surgical excision
What are the possible complications of phaeochromocytoma?
- Cardiac failure
- Myocardial infarction
- Arrhythmias
- Stroke (CVA)
What type of tumour is a phaeochromocytoma?
A rare catecholamine-secreting tumour
Which genetic conditions are associated with phaeochromocytoma?
MEN type II
Neurofibromatosis
Von Hippel-Lindau syndrome
Where is the most common extra-adrenal site for phaeochromocytoma?
The organ of Zuckerkandl, near the aortic bifurcation
What is the first-line test for diagnosing phaeochromocytoma?
Plasma free metanephrines
Why has 24-hour urinary catecholamine testing been replaced?
Because urinary metanephrines have a higher sensitivity (97% vs. 86%)
What is the definitive treatment for phaeochromocytoma?
Surgical removal of the tumour
What is the preoperative medical management of phaeochromocytoma?
- α-blocker first (e.g. phenoxybenzamine)
- β-blocker second (e.g. propranolol)
A 41-year-old man presents with recurrent headaches. These typically occur 2-3 times a day and are associated with sweating and palpitations. As he was concerned that it may be due to blood pressure he borrowed his father’s home monitor. During these episodes, his blood pressure is around 210/110 mmHg. Given the likely diagnosis, what is the most appropriate next test?
24 hour urinary collection of metanephrines
A 35-year-old man has presented to his GP complaining of excessive sweating, headaches, and a feeling of his heart beating in his chest. On measurement of his blood pressure, he is found to be newly hypertensive, on three separate readings. He has a family history of MEN type II.
What is the most appropriate initial investigation for the disease you suspect this man has?
Urinary metanephrines
A 31-year-old man presents with headaches, anxiety and palpitations. On examination, his BP is found to be 195/120mmHg. He is treated for essential hypertension. After failing to respond to initial medical therapy he is further investigated for secondary causes of his hypertension and is diagnosed with pheochromocytoma.
What is the best for control his blood pressure whilst awaiting definitive management of his tumour?
Labetalol
= Both alpha and beta blockade is required when controlling hypertension in pheochromocytoma to avoid hypertensive crises
Phaeochromocytoma typically presents with a triad of what?
(1) sweating
(2) headaches
(3) palpitations
in association with severe hypertension
What is Phenoxybenzamine’s mechanism of action?
Non-specific alpha blocker
What is the medication of choice for peri-operative blood pressure management when treating a phaeochromocytoma?
Phenoxybenzamine
What is the name given to extra-adrenal phaeochromocytomas?
Paragangliomas
Which beta blockers are safe to use in the context of phaeochromocytoma management?
Labetalol
= has combined alpha and beta blocker properties
Where is phaeochromocytoma located?
cells of the adrenal medulla
while a paraganglioma arises in sympathetic nerve tissue elsewhere in the body
A slim 40-year-old woman with a background history of anxiety and palpitations is referred to the hypertension clinic as she has not responded to a combination of 4 anti-hypertensive agents despite good compliance. Initial blood tests are performed which show no evidence of electrolyte abnormalities.
Why would the best investigation be plasma metanephrines rather than short synacthen test?
Plasma metanephrines have the highest sensitivity and specificity of the tests to screen for excess adrenaline metabolites plus a short synacthen test is used to check for adrenal insufficiency which would present with hypotension rather than treatment-resistant hypertension
Tests in order
- Plasma
- If suspicion remains high after a negative serum test then 24-hour urinary
A 54-year-old man presents to the endocrinology clinic. His GP referred him following a suspicious thyroid lump. The patient has undergone a US-guided FNAC which has demonstrated medullary thyroid cancer. A CT scan of the chest and neck reveals no further spread. The patient has a history of asthma and hypertension. as well as intermittent headaches which he finds difficult to control. He normally has ramipril, amlodipine, bendroflumethiazide and atenolol, but still has found it difficult to control his hypertension. On examination, there is a palpable neck mass, but otherwise, there are no abnormalities.
What is the most likely explanation for the intermittent headaches?
Medullary thyroid cancer
= MEN-2 = Phaeochromocytoma
A 60-year-old woman with a background of pheochromocytoma presents with a lump in her neck. She is diagnosed with medullary thyroid cancer.
What gene is associated with this malignancy?
RET oncogene
= MEN 1 X associated with medullary cancer
