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.
What does ACTH stimulate production of?
CRH → ACTH → cortisol and androgen production
