Hperaldosteronism

Question 1

Aldosterone Function

Answer 1

Aldosterone is a mineralocorticoid steroid hormone. It acts on the kidney to:

Increase sodium reabsorption from the distal tubule
Increase potassium secretion from the distal tubule
Increase hydrogen secretion from the collecting ducts

Question 2

Primary Hyperaldosteronism

Answer 2

Primary hyperaldosteronism (Conn’s Syndrome) is when the adrenal glands are directly responsible for producing too much aldosterone. Serum renin will be low as it is suppressed by the high blood pressure. There are several possible reasons for this:

• An adrenal adenoma secreting aldosterone (most common)
• Bilateral adrenal hyperplasia
• Familial hyperaldosteronism type 1 and type 2 (rare)
• Adrenal carcinoma (rare)

Question 3

Secondary Hyperaldosteronism

Answer 3

Secondary hyperaldosteronism is where excessive renin (from the kidneys) stimulating the adrenal glands to produce more aldosterone. Serum renin will be high.

Reduced renal perfusion causes lots of renin to be produced from kidneys:

• Renal artery stenosis
• Renal artery obstruction
• Heart failure
• Liver failure

Question 4

Clinical Features

Answer 4

polyuria
polydipsia
lethargy 
headaches
hypertension

Hyperkalamia -> cardiac arrhtyhmias

Question 5

Investigations

Answer 5

The best screening tool for someone that you suspect has hyperaldosteronism is to check the renin and aldosterone levels and calculate a renin / aldosterone ratio:

• High aldosterone and low renin indicates primary hyperaldosteronism
• High aldosterone and high renin indicates secondary hyperaldosteronism

Other investigations relating to the effects of aldosterone:

• Blood pressure (hypertension)
• Serum electrolytes (hypokalaemia)
• Blood gas analysis (alkalosis)

If a high aldosterone level is found then investigate for the cause:

• Adrenal tumour: CT adrenals + Adrenal Vein Sampling
• Check if renal artery stenosis or obstruction Renal doppler ultrasound, CT angiogram or MRA

Question 6

Management

Answer 6

Aldosterone antagonists

• Eplerenone
• Spironolactone

Treat the underlying cause

Surgical removal of adenoma

Percutaneous renal artery angioplasty via the femoral artery to treat in renal artery stenosis