Primary aldosteronism is the most common specifically treatable and potentially curable form of hypertension. It accounts for at least 5% of hypertensive patients, with most patients being normokalaemic.
Approximately 30% have unilateral forms correctable by unilateral laparoscopic adrenalectomy, and 70% have bilateral forms in which hypertension responds well to aldosterone antagonist medicines.
Optimal detection involves screening all hypertensive patients using the plasma aldosterone/renin ratio, after controlling for factors (including medicines) that may confound results.
In patients with repeatedly elevated aldosterone/renin ratios, definitive confirmation or exclusion of diagnosis involves careful suppression testing with measurement of aldosterone response to fludrocortisone or to salt loading.
Subtype differentiation for optimal treatment involves genetic testing for familial forms where suspected. If genetic testing is not performed or negative, adrenal CT and adrenal venous sampling should be performed to differentiate unilateral from bilateral forms.
In primary aldosteronism (PA), aldosterone production exceeds the body's requirements and is relatively autonomous with regard to its normal chronic regulator, the renin-angiotensin II system. This results in excessive sodium reabsorption via amiloride-sensitive epithelial sodium channels within the distal nephron, leading to hypertension and suppression of renin-angiotensin II. Urinary loss of potassium and hydrogen ions, exchanged for sodium at the distal nephron, may result in hypokalaemia and metabolic alkalosis if severe and prolonged.
History and exam
Key diagnostic factors
- presence of risk factors
Other diagnostic factors
- age 20 to 70 years
- nocturia, polyuria
- mood disturbance (irritability, anxiety, depression)
- difficulty concentrating
- paraesthesias, muscle cramps
- muscle weakness
- family history of PA
- family history of early onset of hypertension and/or stroke
1st investigations to order
- plasma potassium
- aldosterone/renin ratio
Investigations to consider
- fludrocortisone suppression test
- saline infusion testing
- oral salt loading
- genetic testing
- adrenal CT
- adrenal venous sampling
- adrenal MRI
- adrenal selenocholesterol scanning
- posture stimulation testing
- angiotensin II infusion testing
- 24-hour urinary hybrid steroids (18-hydroxy- and 18-oxo-cortisol)
- dexamethasone suppression testing
- ¹¹ C-Metomidate PET/CT
bilateral PA (excluding familial hyperaldosteronism type I)
familial hyperaldosteronism type I
- Essential hypertension (HTN)
- Thiazide-induced hypokalaemia in patient with essential HTN
- Renal artery stenosis
- The 2020 Italian Society of Arterial Hypertension (SIIA) practical guidelines for the management of primary aldosteronism
- The management of primary aldosteronism: case detection, diagnosis, and treatment
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