pheochromocytoma

Question 1

what is pheochromocytoma ?

Answer 1

is a neuroendocrine tumour arising from chromaffin cells of the adrenal medulla

Question 2

what is the clinical presentation of pheochromocytoma?

Answer 2

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

Question 3

what does the adrenal medulla produce ?

Answer 3

catecholamines

Question 4

what stain is used with chromaffin cells

Answer 4

chromium salts stain them brown

Question 5

what are the primary catecholamines ?

Answer 5

adrenaline , noradrenaline and dopamine

Question 6

adrenomedullary cells are called

Answer 6

chromaffin cells

Question 7

when to suspect peochromocytoma?

Answer 7

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

Question 8

what is the pressor response

Answer 8

it is the activation of the sympathetic nervous system which then follows by an increase in plasma catecholamines

Question 9

what is orthostatic hypertension

Answer 9

an increase in systolic and/or diastolic pressure within 3 minutes of standing

Question 10

which enzyme metabolizes catecholamines ?

Answer 10

COMT

Question 11

what are some medications that can increase the level of catecholamines ?

Answer 11

tricyclic antidepressants
ethanol
levodopa
amphetamines

Question 12

what is the most appropiate first line investigation pheochromocytoma ?

Answer 12

1- first line should be plassma free metanephrines
2- 24 hrs urine for catecholamines and metanephrines

Question 13

what is metanephrine ?

Answer 13

a metabolite of epinephrine

Question 14

what is MIBG

Answer 14

MIBG is a nuclear scan test that uses injected radioactive material and a special scanner to locate or confirm the presence of pheochromocytoma

Question 15

what would you ask of the patient before performing an MIBG

Answer 15

if any antipsychotics, tricyclic antidepressant, labetalol or calcium channel blockers are taken then they need to be withdrawn 48hrs before the imaging

Question 16

what other imaging modalities can be used ?

Answer 16

PET scan

Question 17

what is the treatment for pheochromocytoma?

Answer 17

Surgery - laparoscopic or open adrenalectomy

Question 18

what are the steps required preoperatively and what is the target blood pressure ?

Answer 18

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

Question 19

what is an example of a non selective alpha blocker

Answer 19

phenoxybenzamine

Question 20

what are the indications for using beta blockade pre operativley

Answer 20

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

Question 21

what causes a hypertensive crisis?

Answer 21

caused by catecholamine release stimulants such as morphine , ketamine, fentanyl
or by increased intrabdominal pressure
or anxiety

Question 22

how do you treat a hypertensive crisis

Answer 22

Phentolamine (alpha blocker )
OR
Nitroprusside (release NO and cause vasodilatation)
OR
Nicardipine ( Calcium channel blockers)

Question 23

what are the immediate pot op complications ?

Answer 23

hypotension (may presist for 2 months post op) and hypoglycaemia

Question 24

what other steps may you take post op ?

Answer 24

check urine catecholamines post OP and annually

Question 25

What are the three genetic syndromes which are classically associated with pheochromocytoma?

Answer 25

NF1 (neurofibromatosis)
VHL mutation
MEN2A (Multiple endocrine neoplasia)

Question 26

what investigations would you order for a case suspected of pheochromocytoma

Answer 26

24hr urinary cortisol
urinary catecholamines
aldosterone/renin ratio
fasting blood glucose

Question 27

what imagine would you order

Answer 27

MIBG

Question 28

if the results of the biochem comes back normal but the patient clinically appears to have pheochromocytoma what is the next best step in management ?

Answer 28

repeat the test

Question 29

what is the most sensitive modality for identification of pheochromocytomas ?

Answer 29

MRI