Primary hyperaldosteronism (Conn's syndrome) Flashcards
Define primary hyperaldosteronism. Describe the pathophysiology.
Aldosterone production exceeds the body’s requirements and is relatively autonomous with regard to its normal chronic regulator, the renin-angiotensin II system.
What does Conn’s syndrome mean specifically?
Primary hyperaldosteronism caused by an adrenal adenoma
Describe the disturbances caused in primary aldosteronism and their pathophysiology.
- HTN
- Hypokalaemia
- Metabolic alkalosis
Autonomous release of aldosterone causes HTN and suppresses renin production at the JGA.
This results in excessive Na reabsorption in the distal nephron → HTN
Suppression of renin-angiotensin II due to sensing of HTN at the JGA.
Na is exchanged for K and H+ ions which are lost in urine causing a hypokalaemia and metabolic alkalosis.
How common is primary aldosteronism? What condition does it cause?
Most common treatable form of hypertension, accounting for at least 5% of hypertensive patients (most normokalaemic)
What is the aetiology of PHA?
Aetiology of most is unknown
Many have a family history of familial hyperaldosteronism (FH).
What are the risk factors for PHA?
- FH of PA
- FH of early onset hypertension and/or stroke
What are the main causes of primary hyperaldosteronism?
Aldosterone-producing adenoma (Conn’s syndrome) OR carcinoma (rare)
Bilateral OR unilateral adrenal hyperplasia
Aldosterone producing cell clusters
What is the most common cause of primary hyperaldosteronism?
Bilateral adrenal hyperplasia (70% of cases)
What are the signs and symptoms of primary hyperadosteronism?
- Hypertension - may be of early onset
- Nocturia, polyuria - whether or not hypokalaemic
- Lethargy
- Mood disturbance -irritability, anxiety, depression
- Difficulty concentrating
Rare: hypokalaemia may cause paraesthesias, muscle crams, weakness and palpitations.
How do you diagnose PHA?
1st line: Aldosterone/renin ratio -
- best screening test;
- if >20 then likely PHA;
- but false positives/negatives are common.
- Discontinue interfering medicines for at least 2 weeks.
Adrenal CT
Adrenal venous sampling - differentiates between unilateral and bilateral especially if no difference on CT.
Other investigations:
- BP - consider in all patients with resistant hypertension
- Potassium -only 20% are hypokalaemic
- Fludrocortisone suppression test - most reliable. 4 days’ administration of oral fludrocortisone and oral salt loading. Aldosterone fails to suppress.
How is PHA managed?
Adrenal adenoma:
- Laparoscopic adrenalectomy - 70% cured and 100% improved
Bilateral adrenocortical hyperplasia →
- Aldosterone antagonists - e.g. spironolactone /amiloride.
What are the complications of PHA?
- Perioperative - bleeding, infection, wound hernia, CVA.
- Stroke
- MI
- HF
- AF
- impaired renal function
- Aldosterone antagonist/mineralocorticoid receptor antagonist induced hyperkalaemia- bc they are K-sparing, spironolactone, amiloride, and eplerenone can all cause hyperkalaemia.
What is the prognosis with PA?
- Adrenalectomy leads to cure of hypertension in 50-60%
- BP shows improvement in 1-6months
- Recurrence is uncommon
- Aldosterone antagonists work for the majjority and hypokalaemia is almost always corrected
Which adrenal zone is affected in Conn’s?
Zona glomerulosa → aldosterone → Conn’s
NB:
Zona fasciculata → cortisol → Cushing’s
Zona reticularis → androgens → CAH
Medulla → adrenaline (+ sex hormones) → phaeochromocytoma
What is Nelson’s syndrome?
Removal of adrenals causing pituitary enlargement and eventually compression of the stalk causing high ACTH release and so hyperpigmentation.
