Hyperaldosteronism and Conn's Flashcards
What are the 3 main effects of the renin-angiotension-aldosterone system?
- Decrease blood K+
- Increase blood Na+
- Increase blood pressure and volume
Describe the action of aldosterone.
Aldosterone binds to cells in the distal convoluted tubule of nephrons and causes movement of Na and water out of the nephron and potassium and H+ into the nephron. The effect is increased blood sodium and volume, and decreased blood potassium and acidity (alkalinity).
What is primary hyperaldosteronism?
Excess production of aldosterone, independent of the RAAS, causing sodium and water retention and decreased renin release.
What is the most common cause of primary hyperaldosteronism?
Conn’s syndrome: solitary aldosterone-producing adenoma linked to mutations in K+ channels.
Give 2 causes of hyperaldosteronism other than Conn’s syndrome.
Bilateral adrenocortical hyperplasia (usually idiopathic) - increase in aldosterone-secreting cells in ZG
Adrenal carcinoma
What is secondary hyperaldosteronism?
Hyperaldosteronism due to increased renin, eg due to decreased renal perfusion due to heart failure or chronic hypertension.
[OHCM]
Give 3 signs of hyperaldosteronism.
Hypertension, hypokalaemia, metabolic alkalosis (not on diuretics), sodium slightly raised or normal.
Give 3 things in your differential diagnosis for hypertension as well as hyperaldosteronism.
Kidney disease
Diabetes
SLE
Hypothyroidism
Give 3 symptoms of hyperaldosteronism.
(often asymptomatic)
Hypokalaemia -> constipation, weakness, arrythmias
Hypertension -> headaches
Polyuria, polydipsia
How would you diagnose metabolic alkalosis?
pH 7.35–7.45 with increased bicarbonate due to decreased H+.
If renin is low and aldosterone is high, what is the diagnosis?
Primary hyperaldosteronism - high aldosterone causes decreased renin.
Why is K+ an unreliable test in hyperaldosteronism?
20% have normal K+ levels.
How is hyperaldosteronism diagnosed?
High aldosterone, low renin if primary, normal/high renin if secondary.
How is Conn’s syndrome treated?
Laparoscopic adrenalectomy
Spironolactone 4 weeks pre-op to control BP and K+.
What is the class and mechanism of spironolactone?
K+ sparing diuretic; competitively binds to receptors on principal and a-intercalated cells, so the effect of aldosterone is blocked.
