1433 urinary excretion rose to 2 17 1/24 h, with chloride 249 mmol/24 h and potassium 178 mmol/24 h. Mean fall in body weight was 0-29 kg/day. The patient became oedema free over two weeks. Case 4-A 40-year-old man with severe ischaemic heart disease presented with congestive cardiac failure. Blood pressure was 170/90 mm Hg. Piretanide was used in incremental doses up to 24 mg daily. On this dose urinary excretion was 1-0 1/24 h, with sodium 39 mmol/24 h, chloride 35 mmol/24 h, and potassium 35

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... mmol/24 h. Mean fall in body weight was 0-3 kg/day. As oedema persisted, 5 mg metolazone was added. Urinary excretion rose to 2-48 1/24 h, with sodium 210 mmol/24 h, chloride 202 mmol/24 h, and potassium 73 mmol/24 h. Body weight fell by 0-6 kg/day. Oedema cleared over two weeks. Potassium supplements were necessary. Comment Adding relatively small doses of metolazone to high-dose "loop" diuretics significantly increased urine volume and excretion of sodium chloride and potassium, enabling body weight to fall and oedema to clear. The response was immediate and sustained. An initial dose of 2-5 mg metolazone is recommended. Profound natriuresis with associated kaliuresis may lead to hypovolaemia and hypokalaemia respectively. These complications should be anticipated by gradual dose titration according to urine volume and changes in body weight and adequate potassium supplementation. Ideally the patient should be treated with caution in hospital, as dangerous, uncontrolled losses of fluid and electrolytes may occur.4 We are grateful to Sisters M Morris and G Alcock for metabolic nursing, and to Miss J E Davies for secretarial work.