Hyperaldosteronism, Pheochromocytoma

Question 1

when and from where is renin released?

Answer 1

released from the juxtaglomerular cells when decreases in blood pressure are sensed in the glomerulus

Question 2

what are the respective functions of renin and ACE?

Answer 2

renin catalyzes angiotensinogen –> angiotensin I

ACE catalyzes angiotensin I –> angiotensin II

Question 3

how does angiotensin II increase blood pressure? (2)

Answer 3

1. vasoconstriction

2. increase aldosterone release from adrenal cortex

Question 4

function of aldosterone (2) and where it works

Answer 4

1. sodium and water reabsorption
2. potassium and H+ secretion (loss)
   works in distal convoluted tubule

Question 5

2 major symptoms of hyperaldosteronism

Answer 5

hypertension and hypokalemia

Question 6

first test after suspicion of primary hyperaldosteronism

Answer 6

plasma aldosterone:renin activity ratio (should be greater than 20)

Question 7

major difference between primary and secondary hyperaldosteronism

Answer 7

in primary hyperaldosteronism, renin is suppressed, whereas in secondary hyperaldosteronism, renin levels are increased

Question 8

treatment for hyperaldosteronism caused by bilateral adrenal gland tumors

Answer 8

aldosterone receptor antagonist: spironolactone, eplerenone

Question 9

Type I AME: pathogenesis

Answer 9

impaired activity of 11beta-HSD2, which usually inactivates cortisol to cortisone –> cortisol accumulates in the kidney and binds to mineralocorticoid receptors and creates a physiological picture similar to hyperaldosteronism

Question 10

Type I AME: ____tension, ____kalemia, metabolic ____osis, _____ renin activity, _____ aldosterone, and _____ plasma cortisol levels

Answer 10

hypertension; hypokalemia, metabolic alkalosis, low renin activity, low aldosterone, normal plasma cortisol levels

Question 11

Type I AME: treatment

Answer 11

mineralocorticoid receptor antagonists: spironolactone, eplerenone

Question 12

Liddle syndrome: pathogenesis

Answer 12

mutations in epithelial sodium channel –> enhanced activity of the sodium channel causing increased sodium reabsorption, potassium wasting, hypertension, and hypokalemia

Question 13

Liddle syndrome: ____tension, ____kalemia, _____ renin activity, _____ aldosterone, and _____ plasma cortisol levels

Answer 13

hypertension, hypokalemia, low renin activity, low aldosterone, normal plasma cortisol levels

Question 14

Liddle syndrome: treatment

Answer 14

potassium-sparing diuretics: amiloride and triamterene

Question 15

1. dx: high renin, high aldosterone

2. dx: low renin, high aldosterone

Answer 15

1. secondary hyperaldosteronism

2. primary hyperaldosteronism

Question 16

block the effects of aldosterone at the receptor level (2)

Answer 16

spironolactone and eplerenone

Question 17

pathogenesis of pheochromocytoma vs. paraganglioma

Answer 17

pheochromocytoma: tumor of chromaffin cells of adrenal medulla
paraganglioma: tumor that arises from extra-adrenal ganglia of the sympathetic nervous system

Question 18

what are adrenal medullary (chromaffin cells) made of?

Answer 18

modified postganglionic sympathetic nerves that lack axons and secrete their neurotransmitter (mainly epinephrine) directly into the blood

Question 19

what do pheochromocytomas and paragangliomas respectively secrete? what is responsible for this difference?

Answer 19

pheochromocytomas: epinephrine and norepinephrine
paragangliomas: norepinephrine
cortisol bathes the adrenal medulla and cortisol induces expression of PNMT, which converts norepinephrine into epinephrine

Question 20

dx: hypertension, sweating, headaches, palpitations

Answer 20

pheochromocytoma

Question 21

2 diagnostic tests for pheochromocytoma

Answer 21

plasma free metanephrines and urinary catecholamines

Question 22

best way to image a pheochromocytoma

Answer 22

CT abdomen/adrenal glands

Question 23

treatment of pheochromocytoma

Answer 23

alpha blockade (phrnoxybenzamine) followed by beta-blockers (prior to tumor resection