pheochromocytoma Flashcards
what is pheochromocytoma ?
is a neuroendocrine tumour arising from chromaffin cells of the adrenal medulla
what is the clinical presentation of pheochromocytoma?
generally sympatheticc systemm overdrive
hypertension
orthostatic hypertension
light headedness
syncope, pre syncope
spells of palpitations, tremors, sweating may be induced by exercise, meds or a change in position
may also be accompanied by anxiety of impending death
what does the adrenal medulla produce ?
catecholamines
what stain is used with chromaffin cells
chromium salts stain them brown
what are the primary catecholamines ?
adrenaline , noradrenaline and dopamine
adrenomedullary cells are called
chromaffin cells
when to suspect peochromocytoma?
1- when there is resistant hypertension
2- familial history of pheochromocytoma
3- patients with a pressor response during anesthesia
4- patients with onset of hypertension at a young age
5- patients with idiopathic dilated cardiomyopathy
what is the pressor response
it is the activation of the sympathetic nervous system which then follows by an increase in plasma catecholamines
what is orthostatic hypertension
an increase in systolic and/or diastolic pressure within 3 minutes of standing
which enzyme metabolizes catecholamines ?
COMT
what are some medications that can increase the level of catecholamines ?
tricyclic antidepressants
ethanol
levodopa
amphetamines
what is the most appropiate first line investigation pheochromocytoma ?
1- first line should be plassma free metanephrines
2- 24 hrs urine for catecholamines and metanephrines
what is metanephrine ?
a metabolite of epinephrine
what is MIBG
MIBG is a nuclear scan test that uses injected radioactive material and a special scanner to locate or confirm the presence of pheochromocytoma
what would you ask of the patient before performing an MIBG
if any antipsychotics, tricyclic antidepressant, labetalol or calcium channel blockers are taken then they need to be withdrawn 48hrs before the imaging
what other imaging modalities can be used ?
PET scan
what is the treatment for pheochromocytoma?
Surgery - laparoscopic or open adrenalectomy
what are the steps required preoperatively and what is the target blood pressure ?
alpha and beta blockade, for the alpha blockade must be used at least 7-10 days preoperatively then beta blockade 2-3 days pre op ( use propranolol )
target blood pressure to be no more than 120/80 sitting
what is an example of a non selective alpha blocker
phenoxybenzamine
what are the indications for using beta blockade pre operativley
can only be used after adequate alpha blockade (never use unopposed beta blockade) , and beta blockade must be used 2-3 days preoperatively , the beta blocker used can be propanolol or bisoprolol
what causes a hypertensive crisis?
caused by catecholamine release stimulants such as morphine , ketamine, fentanyl
or by increased intrabdominal pressure
or anxiety
how do you treat a hypertensive crisis
Phentolamine (alpha blocker ) OR Nitroprusside (release NO and cause vasodilatation) OR Nicardipine ( Calcium channel blockers)
what are the immediate pot op complications ?
hypotension (may presist for 2 months post op) and hypoglycaemia
what other steps may you take post op ?
check urine catecholamines post OP and annually
