In extolling the benefits of potassium an editorial in the BMJ recently advocated that people should increase their intake of potassium.1 Its benefits include lowering blood pressure in both hypertensive and normotensive people. A high potassium intake reduces the risk of stroke, and in rats it prevents renal vascular, glomerular, and tubular damage. Increasing potassium concentrations also reduces the risk of ventricular arrhythmias in patients with heart disease, heart failure, and left ventricular hypertrophy.1 Using a salt substitute that contains potassium combines the advantages of reducing sodium intake and increasing potassium intake.

However, in the high risk population that may benefit most from an increased consumption of potassium, several medical conditions predispose to the development of hyperkalaemia through impairing renal excretion of potassium. These conditions include renal failure, diabetes mellitus with hyporeninaemic hypoaldosteronism, and obstructive uropathy. The risk of hyperkalaemia is further increased by the frequent prescription in these patients of angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, and potassium sparing diuretics.2 Elderly patients with osteoarthritis may also use non-steroidal anti-inflammatory drugs, which also may contribute to increased plasma potassium values. …