A 53-year-old man presented with hypertension of 150/110 mmHg. He is generally asymptomatic and has no previous medical history of note. He is a smoker of 5 cigarettes daily and drinks modest quantities of alcohol. He takes no prescribed medications. Examination reveals a BMI of 33.5 kg/2 but nil else. The following detail his investigations: Serum sodium 146 mmol/l (NR 133-145) Serum potassium 3.2 mmol/l (NR 3.5 - 5) Urinary potassium excretion 42 mmol/l (NR less than 30) What is the likely diagnosis? 1) Adrenocortical adenoma 2) Bartter's syndrome 3) Liddle's syndrome 4) Liquorice ingestion 5) Pheochromocytoma