Hyperaldosteronism

Question 1

Recap physiology of aldosterone secretion?

Answer 1

• afferent arteriole contains the juxtaglomerular cells which sense BP and secrete Renin in response to low BP
• Liver secretes angiotensinogen
• Renin converts Angiotensingogen into Angiotensin I
• ACE made in the lungs converts Angiotensin I into Angiotensin II
• Angiotensin II cause release of aldoseterone from adrenal glands

Question 2

What does aldosterone do?

Answer 2

• Increases sodium reabsorption from the distal tubule
• increases potassium secretion from the distal tubule
• increases hydrogen secretion from collecting duct

Question 3

What is primary hyperaldosteronism?

What do you find in this condition?

Answer 3

Conn’s Syndrome

when the adrenal glands are directly responsible for producing too much aldosterone

Serum renin is low due to suppression by high BP

Question 4

What are the causes of primary hyperaldosteronism?

Answer 4

1. Bilateral adrenal hyperplasia - most common
2. Adranl adenoma
3. Familial hyperaldosteronism type 1 and type 2 (rare)
4. Adrenal carcinoma (rare)

Question 5

What are the features of primary hyperaldosteronism?

Answer 5

hypertension

hypokalaemia leading to - muscle weakness

Alkalosis

Low renin levels as it is suppressed by high BP

Question 6

What is secondary hyperaldosteronism?

How can you differentiate from primary?

Answer 6

Where there is excessive renin stimulating adrenal gland to produce more aldosterone

serum renin will be high

Question 7

What are the causes of secondary hyperaldosteronism?

Answer 7

high renin levels are caused by BP - reduced perfusion- in the kidneys being disproportionately lower than the rest of the body

1. renal artery stenosis (caused by atheroscleorosis)
2. renal artery obstruction
3. heart failure

Question 8

What investigations would you do for hyperaldosteronism?

Answer 8

1st line
Plasma aldosterone:renin ration
- high aldosterone and low renin in PRIMARY (negative feedback due to Na+ retention)
- high aldosterone and high renin in SECONDARY

Other investigations

• BP: htn
• Blood gas - alkalosis
• U+E’s - hypokalaemia (> 20% normal tho)
• high resolution CT abdomen for adrenal tumour
• Adrenal veinous sampling (to identify gland secreting excess hormone)

Question 9

What is the management of hyperaldosteronism

Answer 9

Adrenal adenoma - surgery

Bilateral adrenal hyperplasia: aldosterone antagonists e.g Spironolactone

Percutaenous renal artery angioplasty for renal artery stenosis

Question 10

What is especially important to remember about hyperaldosteronism?

Answer 10

most common cause of secondary hypertension

if patient is not responding to BP tx consider screening for hyperaldestornism with renin:aldosterone ratio

key clue is hypokalaemia but this can be norma;