Pheochromocytoma

Question 1

are basically modified postganglionic nerves that lack axons and secrete their neurotransmitter (mainly epinephrine) directly into the blood; thus, the bloodstream acts like a giant synapse, carrying epinephrine to receptors throughout the body.

Answer 1

Adrenal medullary (chromaffin) cells

Question 2

are tumors of the chromaffin cells of the adrenal medulla

Answer 2

Pheochromocytoma

Question 3

are tumors that arise from extra-adrenal ganglia of the sympathetic nervous system.

Answer 3

Paragangliomas

Question 4

Pheochromocytomas can secrete excessive amounts of both ___________, whereas paragangliomas and metastases of pheochromocytomas generally secrete primarily_____

Answer 4

epinephrine and norepinephrine

norepinephrine

Question 5

What is our RLS in formation of epi and norepi

Answer 5

tyrosine hyroxylase

Question 6

What is expressed more in the adrenall medulla then sympathetic nerves so that Nepi is our primary product of SNS while Epi is the primary product from adrenal medulla?

Answer 6

PNMT

Question 7

What is the cause of our manifestation of symptoms from pheochromocytomas?

Answer 7

catecholamie excess

***see Fight or Flight type sytmpoms

Question 8

The classic symptoms of pheochromocytomas are

Answer 8

hypertension (90% of patients),

headaches (80%),

diaphoresis (70%),

and palpitation (60%).

These symptoms are mediated by catecholamine excess.

Question 9

Patients who undergo removal of pheochromocytomas are usually _____ and need large amounts of fluid to compensate when the offending lesion is removed and catecholamine levels fall rapidly.

Answer 9

volume constricted

Question 10

You suspect pt has pheochromocytoma, what 24 hr URINARY test would you order?

Answer 10

Catecholamines

Question 11

You suspect pt has pheochromocytoma, what PLASMA test do you order?

Answer 11

Free metanaphrines

slightly more sensitive the catecholamine test

Question 12

Only after biochemical confirmation of a pheochromocytoma is secured should imaging be obtained to locate the causative lesion. The best imaging test is

Answer 12

CT scan of the abdomen/adrenal glands.

Question 13

If CT is not able to identify a causative lesion or there is question about a lesion what other functional imaging can be used?

Answer 13

MIBG scanning uses 131Iodine tagged MIBG (iodine-131-meta-iodobenzylguanidine) to identify pheochromocytomas.

Question 14

WHy can we use an octreotide scan do dx pheochromocytoma?

Answer 14

they occasionally express somatostain receptors

Question 15

The only curative therapy for pheochromocytoma is

Answer 15

surgical removal of the tumor. Unilateral adrenalectomy of the effected gland is the preferred therapy.

Question 16

What is dangerous about removing a pheochromocytoma?

Answer 16

During surgical removal of a pheochromocytoma the manipulation of the tumor can cause release of excessive amounts of catecholamines. This surge in catecholamines can cause profound vasoconstriction and resultant hypertensive emergency.

Question 17

During surgical removal of a pheochromocytoma the manipulation of the tumor can cause release of excessive amounts of catecholamines. This surge in catecholamines can cause profound vasoconstriction and resultant hypertensive emergency, how can we appropriately prep pts?

Answer 17

should be treated with alpha-adrenergic blockers so that catecholamine induced vasoconstriction is prevented.

Question 19

is a nonselective alpha blocker with a long half-life of about 24 hours. It does not block the synthesis of catecholamines; in fact, the synthesis of catecholamines and metanephrines tends to increase during alpha blockade.

Answer 19

Phenoxybenzamine

Question 20

synthesis of catecholamines and metanephrines tends to increase during alpha blockade thus patients should be treated with alpha blockers until they are

Answer 20

normotensive or develop orthostasis

Question 21

Therapy with alpha blockers tends to increase the heart rate so after appropriate alpha blockade is achieved _______ should be used to help decrease tachycardia

Answer 21

beta-adrenergic blockade