Phaeochromocytoma Flashcards
What is a phaeochromocytoma?
A phaeochromocytoma is a tumour of the adrenal glands that secretes unregulated and excessive amounts of catecholamines (adrenaline).
Where is adrenaline produced in the body?
Adrenaline is produced by the chromaffin cells in the medulla (middle part) of the adrenal glands.
What is the main function of adrenaline in the body?
Adrenaline stimulates the sympathetic nervous system and is responsible for the “fight or flight” response.
How does a phaeochromocytoma affect adrenaline secretion?
In a phaeochromocytoma, the tumour secretes excessive amounts of adrenaline, usually in bursts, leading to intermittent symptoms.
What are some genetic disorders associated with phaeochromocytomas?
- Multiple endocrine neoplasia type 2 (MEN 2)
- Neurofibromatosis type 1
- Von Hippel-Lindau disease
What is the 10% rule for phaeochromocytomas?
The 10% rule refers to the following patterns of phaeochromocytomas:
* 10% are bilateral
* 10% are cancerous
* 10% are outside the adrenal gland
What are the common signs and symptoms of phaeochromocytomas?
Symptoms relate to excessive adrenaline secretion and can include:
* Anxiety
* Sweating
* Headache
* Tremor
* Palpitations
* Hypertension
* Tachycardia
What are the initial tests for diagnosing phaeochromocytoma?
- Plasma free metanephrines
- 24-hour urine catecholamines
Why are plasma catecholamine levels not reliable for diagnosing phaeochromocytomas?
Plasma catecholamine levels fluctuate and have a very short half-life (around a minute), making them unreliable for diagnosis.
Why are metanephrines measured in phaeochromocytoma diagnosis?
Metanephrines, a breakdown product of adrenaline, have a longer half-life and more stable levels, making them more reliable for diagnosis.
What imaging tests can be used to locate a phaeochromocytoma?
CT or MRI can be used to locate the tumour.
Is genetic testing recommended in phaeochromocytoma diagnosis?
Yes, genetic testing may be advised to look for a genetic cause, including testing of relatives.
What is the main treatment for phaeochromocytoma?
- Alpha blockers (e.g., phenoxybenzamine or doxazosin)
- Beta blockers (only after alpha blockers)
- Surgical removal of the tumour
Why are alpha blockers used in the management of phaeochromocytomas?
Alpha blockers are used to control symptoms before surgery to reduce the risk of complications during anaesthesia and surgery.
What is the role of beta blockers in phaeochromocytoma treatment?
Beta blockers are used only after the patient has been stabilized on alpha blockers to prevent a hypertensive crisis.
