endocrine

Question 1

Hypertension, hypernatremia and hypokalemia. Middle aged man, new presentation. What is the Dx?

Answer 1

Primary hyperaldosteronism

Question 2

Commonest cause of primary hyperaldosteronism

Answer 2

bilateral idiopathic adrenal hyperplasia
Other cause: Conn’s syndrome (adrenal adenoma), unilateral hyperplasia
familial hyperaldosteronism
adrenal carcinoma

Question 3

How does aldosterone increase BP

Answer 3

Aldosterone increases BP through prior activation of the RAAS system whereby renin is produced in reaction to low BP, causing angiotensin and aldosterone production. This then causes water retention through Na absorption and K loss.

Question 4

Why do you get a metabolic alkalosis in primary hyperaldosteronism

Answer 4

Loss of hydrogren ions through movement into cells and loss of hydrogen from the extracellular space

Question 5

clinical sign of hypokalemia

Answer 5

muscle weakness

Question 6

Ix if primary hyperaldosteronism is suspected

Answer 6

aldosterone/renin ratio is the first-line investigation in suspected primary hyperaldosteronism
should show high aldosterone levels alongside low renin levels (negative feedback due to sodium retention from aldosterone)

following this a high-resolution CT abdomen and adrenal vein sampling is used to differentiate between unilateral and bilateral sources of aldosterone excess
if the CT is normal adrenal venous sampling (AVS) can be used to distinguish between unilateral adenoma and bilateral hyperplasia