Measure serum potassium concentration in hypertensive patients as an initial investigation. Suspect primary aldosteronism if a hypertensive patient presents with spontaneous hypokalaemia in the absence of diuretic use or hypokalaemia during low-dose diuretic use (serum potassium < 3.5 mmol/l in the absence of diuretic use or < 3.0 mmol/l during low-dose diuretic use). treatment-resistant hypertension adrenal incidentaloma early onset hypertension (under 40 years of age) or stroke.
