Hyperaldosteronism

Question 1

What is the effect of aldosterone?

Answer 1

Renal water and sodium retention

Potassium and H+ excretion

Question 2

What are some drugs that affect the renin-angiotensin-aldosterone system?

Answer 2

1. direct renin inhibitors
2. ACE inhibitors
3. Angiotensin receptor blockers (ARB)
4. Mineralcorticoid receptor antagonist

Question 3

What are some things that may cause primary hyperaldosteronism?

Answer 3

Adrenal hyperplasia
Aldosterone-secreting adrenal adenoma

Htn, hypokalemia, metabolic alkalosis and low plasma renin

Question 4

When should you consider testing of primary aldosteronism?

Answer 4

1. hypertension and hypokalemia
2. resistant hypertension (3 drugs and poor BP control)
3. Adrenal incidentaloma and hypertension
4. Onset of hypertension at a young age (<30)
5. Severe hypertension

Question 5

What blood tests you should run if testing for primary aldosteronism?

Answer 5

Plasma aldosterone concentration (PAC) >15 ng/dL

Plasma renin activity or plasma renin concentration (PRC) 20 ng/dL

Question 6

What are some causes of secondary hyperaldosteronism?

Answer 6

Renal ischemia
Decreased intravascular volume
CHF
Chronic diuretic or laxative use
Hypoproteinemia states (cirrhosis, nephrotic syndrome)
Sodium-wasting disorders
Chronic renal failure

Question 7

When working up for primary hyperaldosteronism how do you proceed if the CT or MRI scan of the adrenals is normal?

Answer 7

Selective venous catheterization for aldosterone and cortisol

Unilateral increased aldosterone –> Adrenalectomy

Bilateral hyper function or failure to localize –> Medical management

Question 8

What are some medications used for medical management of bilateral adrenal disease?

Answer 8

Mineralocorticoid receptor antagonists
Block the effects of aldosterone at the receptor level
Spironolactone and Eplerenone
Decrease sodium and water retention
Also increase serum potassium levels as less potassium is secreted into renal tubules

Question 9

What protects the mineralocorticoid receptor in the renal tubule from activation by cortisol?

Answer 9

11B-hydroxysteroid dehydrogenase type 2 (11B-HSD2)

Question 10

Mutations in the amiloride-sensitive epithelial sodium channel

Answer 10

Liddle’s Syndrome

Treat with amiloride and triamterene (potassium sparing diuretics)

Question 11

Apparent mineralocorticoid excess

Answer 11

11BHSD2 deficiency

Question 12

What is the rate limiting step in catecholamine synthesis?

Answer 12

Tyrosine hydroxylase

Question 13

What does PNMT do?

Answer 13

Enzyme that takes norepinephrine to epinephrine

Question 14

Where is PNMT expressed?

Answer 14

Much more in adrenal medulla than sympathetic nerves os that Norepi is the primary product of the SNS while Epi is the primary product of the adrenal medulla

Question 15

Tumors of the chromatin cells of the adrenal medulla

Often secrete excessive amounts of both epinephrine and norepinephrine

Answer 15

Pheochromocytoma

Question 16

Tumors that arise from extra-adrenal ganglia of the sympathetic nervous system
Secrete primarily norepinephrine

Answer 16

Paragangliomas

Metastases of pheochromocytoma

Question 17

What biochemical tests do you do to determine if someone has pheochromocytoma??

Answer 17

24 h urinary tests for catecholamines and free metanephrines

Question 18

What do you do after biochemical tests point to pheochromocytoma?

Answer 18

Imaging tests (CT, MRI)

Question 19

What is the treatment for pheochromocytoma?

Answer 19

1. Begin alpha blockade (phenoxybenzamine)
2. Begin beta-adrenergic blockade to treat tachycardia (only after alpha blockade is achieved)
3. Appropriate hydration
4. Surgical therapy with adrenalectomy