Hyperaldosteronism (& Conn's)

Question 1

Define primary hyperaldosteronism

Answer 1

Excess production of aldosterone, independent of renin-angiotensin system

Causing ↑Na+ & water retention & ↓renin release

Question 2

Outline the symptoms & signs of primary hyperaldosteronism

Answer 2

• Often asymptomatic
• Hypokalaemia (weakness, cramps, paraethesiae, polyuria, polydipsia)
• Hypertension (due to hypernaturaemia)
• Metabolic alkalosis (H+ loss)

Question 3

Outline the causes of primary hyperaldosteronism

Answer 3

• 2/3 due to solitary aldosterone-producing adenoma (CONN’s SYNDROME!)
• ~1/3 bilateral adrenocortical hyperplasia

Rare;

• Adrenal carcinoma
• Glucocorticoid-remediable aldosteronism (GBA, where ACTH regulatory element of 11B-hydroxylase gene fuses to aldosterone synthase = ↑aldosterone)

Question 4

Define Conn’s syndrome

Answer 4

Primary hyperaldosteronism caused by a solitary aldosterone-producing adenoma

Question 5

Outline the investigations in primary hyperaldosteronism

Answer 5

Think of Conn’s if;

• ↑BP + ↓K⁺
• ↑BP despite 3 antihypertensive trials (refractory hypertension)
• ↑BP <40yrs

→Confirm primary hyperaldosteronism;

• Aldosterone/renin ratio
  
  • Discontinue anti-↑BP, use a-blockers temp
  • ↑A:↓R indicative of primary hyperaldosteronism
• Suppression tests
  
  • Flludrocortisone/ saline/ high sodium diet
  • Normally suppress aldosterone secretion
  • 24hr urinary aldosterone secretion >14ug = diagnostic

→ Differentiating Conn’s or bilateral adrenocortical hyperplasia

• Renin, aldosterone & cortisol measured after lying overnight AND when upright for 4 hours
• Standing → ↑renin → ↑aldosterone
• Exaggerated in bilateral adrenocortical hyperplasia
• No effect in Conn’s as aldosterone production is autonomous

Imaging

• CT/ MRI
  
  • To localise the cause after confirming primary hyperaldosteronism (due to a high number of adrenal incidentalomas)
  • Unilateral adenoma = surgery
• DXM suppression test
  
  • Suppresses ACTH, causing ↓aldosterone
• Adrenal vein sampling
  
  • One side producing more aldosterone than the other = adenoma likely
• Adrenal scintigraphy

Question 6

What is secondary hyperaldosteronism?

What are some causes?

Answer 6

↓Renal perfusion → ↑Renin → ↑Aldosterone

Causes;

• Renal artery stenosis
• Accelerated hypertension
• Diuretics
• CCF
• Hepatic failure

Question 7

What is Bartter’s syndrome?

Answer 7

Congenital (ar) salt wasting (NaCl leak in loop of Henle)

Presentation;

• Childhood
• Failure to thrive
• Polyuria
• Polydipsia
• Normal BP
• Na loss → volume depletion, ↑renin & ↑aldosterone production
• Leading to hypokalaemia, metabolic alkalosis