Screening for primary aldosteronism.

Normokalaemic manifestation of primary aldosteronism is a frequent cause of secondary hypertension. It occurs in approximately 5-12% of all patients with hypertension, primarily patients with severe and uncontrolled blood pressure. Main causes are bilateral adrenal hyperplasia (2/3 of cases) and aldosterone-producing adenoma (1/3 of cases). Screening is performed by measurement of the aldosterone/renin ratio, which is raised in affected patients. Suspicion of primary aldosteronism due to a pathological ratio requires confirmatory testing e.g. by saline infusion test or fludrocortisone suppression test. If the diagnosis is confirmed, the underlying cause of aldosterone excess needs to be identified because therapy differs. First, adrenal imaging (CT/MRI) is performed, which is followed by postural testing in cases with a unilateral lesion. Concordant results confirm the diagnosis of an aldosterone-producing adenoma and allow treatment to proceed to adrenalectomy. In cases of equivocal results or normal/bilaterally enlarged adrenal glands on imaging, adrenal venous sampling must be performed for subtype differentiation.