- Serum potassium concentration of more than 5.0 mmol/L before randomisation; evidence of renal impairment defined as serum creatinine>133 umol/L or creatinine clearance of <60 mL/min; known significant renal stenosis (>70%) of one or both renal arteries; evidence of liver disease (i.e. cirrhosis or hepatitis) or abnormal liver function defined as aspartate aminotransferase, alanine aminotransferase or total bilirubin >1.5x the upper limit of normal; evidence of primary aldosteronism (plasma aldosterone/renin ratio>650 pmol/L); electrolyte imbalance; active gout; use of MR antagonists; use of potassium-sparing diuretics, or potassium supplements; individuals with claustrophobia or a history of any metallic prosthetic implant contraindicating MRI.