Primary Hyperaldosteronism

Question 1

Definition

Answer 1

Characterised by autonomous aldosterone overproduction from the adrenal gland with subsequent suppression of plasma renin activity

Question 2

Aetiology/Risk factors

Answer 2

· Adrenal adenoma (Conn’s syndrome) - responsible for 70% of cases

· Adrenal cortex hyperplasia (30% of cases)

· RARE:
o Glucocorticoid-suppressible hyperaldosteronism
o Aldosterone producing adrenal carcinoma

Question 3

Pathophysiology

Answer 3

o Excess aldosterone leads to increased Na+ and water retention

o This leads to hypertension

o It also causes increased renal K+ loss leading to hypokalaemia

o Renin is suppressed due to NaCl retention

Question 4

Epidemiology

Answer 4

· 1-2% of hypertensive patients

· Conn’s syndrome is more common in WOMEN and YOUNG patients

· Bilateral adrenal hyperplasia is more common in MEN and presents at an older age

Question 5

Presenting symptoms

Answer 5

· Usually ASYMPTOMATIC

· Tends to be an incidental finding on routine blood tests

· Symptoms of HYPOkalaemia
o Muscle weakness
o Polyuria and polydipsia (due to nephrogenic DI)
o Paraesthesia
o Tetany

Question 6

Signs on physical examination

Answer 6

· Hypertension

· Complications of hypertension (e.g. hypertensive retinopathy)

Question 7

Investigations (screening tests)

Answer 7

o Low Serum K+
· NOTE: Serum Na+ is usually normal because the Na+ reabsorption is matched by water reabsorption

o High Urine K+

o High Plasma Aldosterone Concentration

o High aldosterone: renin activity ratio

Question 8

Investigations (confirmatory tests)

Answer 8

o Salt Loading
· Failure of aldosterone suppression following salt load confirms primary hyperaldosteronism

o Postural Test
· Measure plasma aldosterone, renin activity and cortisol when the patient is lying down at 8 am
· Measure again after 4 hrs of the patient being upright
· Aldosterone-producing adenoma - aldosterone secretion decreases between 8 am and noon
· Bilateral adrenal hyperplasia - adrenals respond to standing posture and increase renin production leading to increased aldosterone secretion

o CT/MRI

o Bilateral adrenal vein catheterisation
· Measures adrenal vein aldosterone levels and allows you to distinguish between Conn’s syndrome and bilateral adrenal hyperplasia

o Radio-labelled cholesterol scanning
· Unilateral uptake in adrenal adenomas
· Bilateral uptake in bilateral adrenal hyperplasia

Question 9

Management plan (bilateral adrenal hyperplasia)

Answer 9

o Spironolactone (potassium-sparing diuretic)

o Eplerenone can be used if the spironolactone side-effects are intolerable

o Amiloride (potassium-sparing diuretic)

o Monitor serum K+, creatinine and BP

o ACE inhibitors and CCBs may also be added

Question 10

Management plan (aldosterone producing adenomas and adrenal carcinoma)

Answer 10

· Aldosterone Producing Adenomas
o Adrenalectomy

· Adrenal Carcinoma
o Surgery
o Post-operative mitotane (antineoplastic)

Question 11

Possible complications

Answer 11

Complications of hypertension

Question 12

Prognosis

Answer 12

· Surgery may cure hypertension

· Or it may make the hypertension easier to treat with anti-hypertensive medication