Conn's syndrome Flashcards
What is essential hypertension
90% of hypertension
no cause can be found
what is primary hyperaldosteronism?
when high aldosterone levels exist independently of the renin-angiotensin system
What are the causes of primary hyperaldosteronism?
- adrenal adenoma secreting aldosterone (Conn’s syndrome)
2. bilateral adrenal hyperplasia
What effect does excess aldosterone have?
increased Na/K exchange in the distal renal tubule (absorption of Na and excretion of K by the ENaC transporter)
–> hypertension with hypokalaemia
Renal effects of low K+
reversible nephrogenic diabetes insipidus - thirst, polyuria, nocturia
Neuromuscular effects of low K+
muscle weakness, flaccid paralysis, tetany, parasethesiae
what other cases of low K+ must be excluded?
diuretics, laxatives, diet, GI loss
whats the initial screening test for primary hyperaldosteronism?
plasma aldosterone: renin ratio (ARR)
stop antihypertensive drugs- except alpha blockers + Ca channel blockers
how is the diagnosis of primary hyperaldosteronism made?
demonstrate increased plasma aldosterone levels that aren’t suppressed with 0.9% saline infusion, or fludrocortisone administration (a mineralocorticoid)
how to establish the cause of primary hyperaldosteronism?
CT or MRI of the adrenals
where is aldosterone produced?
the adrenal zona glomerulosa - which secretes mineralocorticoids
Mx of adenomas (Conn’s)?
removed surgically - adrenalectomy: usually laparoscopically
Mx of bilateral adrenal hyperplasia
BP control
aldosterone antagonist
- spironalactone
mechanism of action of aldosterone antagonist
competitively bind to the aldosterone receptor
Side effects of aldosterone antagonist
hyperkalaemia - muscle weakness, arrhythmias, cardiac arrest
gynaecomastia
liver impairment, jaundice
