Hyperaldosteronism

Question 1

Explain the physiology of the RAAS, which results in the production of aldosterone

Answer 1

In the afferent arteriole in the kidney there are juxtaglomerular cells sense the BP in these vessels. If there’s low BP in the arteriole they secrete renin. The liver secretes angiotensinogen. Renin acts to convert angiotensinogen to angiotensin I. ACE I converts Angiotensin I to angiotensin II in the lungs. Angiotensin II stimulates the release of aldosterone from the adrenal glands

Question 2

1) What 2 things does aldosterone do in the distal tubule?
2) What does aldosterone do in the collecting ducts?

Answer 2

1) Increase sodium reabsorption and potassium excretion
2) Increase hydrogen secretion

Question 3

1) What is the pathology in primary hyperaldosteronism?
2) What will this cause to happen to serum renin levels, and why?
3) Name a cause of this pathology

Answer 3

1) Adrenal glands are directly responsible for producing too much aldosterone
2) Low, suppressed by high BP caused by excessive aldosterone
3) Bilateral adrenal hyperplasia (most common), adrenal adenoma secreting aldosterone (Conn’s Syndrome), familial hyperaldosteronism type 1 and type 2 (rare), adrenal carcinoma (rare)

Question 4

1) What is the pathology in secondary hyperaldosteronism?
2) When would this pathology occur?
3) Name a cause of this pathology?

Answer 4

1) Excessive renin stimulating the adrenal glands to produce more aldosterone
2) BP in the kidney is disproportionately lower than the BP in the rest of the body
3) Renal artery stenosis, renal artery obstruction, heart failure

Question 5

1) What is the usual cause of renal artery stenosis?
2) Name an investigation for renal artery stenosis

Answer 5

1) Atherosclerosis
2) doppler ultrasound, CT angiogram or magnetic resonance angiography (MRA)

Question 6

1) In primary hyperaldosteronism, what would be seen in the levels of renin and aldosterone
2) In secondary hyperaldosteronism, what would be seen in the levels of renin and aldosterone?
3) Name another investigation that may be used (related to the result of hyperaldosteronism)

Answer 6

1) High aldosterone, low renin
2) High aldosterone, high renin
3) BP (hypertension - big cause of secondary hypertension), serum electrolytes (hypokalaemia), blood gas analysis (alkalosis)

Question 7

1) Name an aldosterone antagonist that may be used
2) Treatment can also involve treatment of the underlying cause, give an example of this

Answer 7

1) Eplerenone, spironolactone
2) Removal of adrenal tumour, percutaneous renal artery angioplasty (via femoral artery)

Question 8

What is the 1st line investigation for primary hyperaldosteronism?

Answer 8

Serum renin:aldosterone ratio

Question 9

1) Following a serum renin:aldosterone ratio, what can be done to differentiate between a unilateral and a bilateral source of aldosterone excess?
2) If this is normal, what’s the next investigation done to differentiate between bilateral and unilateral sources?

Answer 9

1) High resolution abdo CT
2) Adrenal venous sampling

Question 10

When investigating for primary hyperaldosteronism, what drugs should be stopped, and how long should they be stopped for?

Answer 10

• Diuretic 4 weeks
• Beta blockers and dihydropyridine CCBs 2 weeks
• Steroids, potassium supplements and laxatives should also be stopped