Metabolic acidosis, hypokalaemia and acute renal failure with a normal urine output.

A 72-year-old man was admitted with a 3-week history of general debility and diarrhoea, passing copious amounts of watery, brown stool through the day and Question night. He had had no abdominal pain and had started to vomit the day before presentation. On examination What is the most likely diagnosis? Why is the patient he was dehydrated and mildly disorientated. He had a polyuric in the face of profound dehydration? tachycardia of 110/min, and a blood pressure of 90/70 mmHg, with a postural drop to 60/30 mmHg. Table 1. Initial results His abdomen was soft and non-tender, with tinkling bowel sounds. No masses were felt on palpation or Biochemistry on presentation Normal range rectal examination. His biochemistry on presentation is shown on Table 1. Sodium 121 mmol/l (135–145 mmol/l ) His stool volume was recorded in excess of 3 l per Potassium 2.9 mmol/l (3.5–5.0 mmol/l ) day, and with a urine output of 50 to 100 ml/h. Dipstix Chloride 83 mmol/l (95–110 mmol/l ) testing showed a trace of haematuria and proteinuria Bicarbonate 6 mmol/l (22–26 mmol/l ) with the presence of ketones. A chest X-ray was Urea 90 mmol/l (2.8–8.9 mmol/l ) Creatinine 960 mmol/l (75–115 mmol/l ) normal, and a plain film of the abdomen showed Glucose 4.9 mmol/l (3.9–6.1 mmol/l ) occasional loops of non-dilated bowel. He had normal pH 7.261 (7.35–7.45 pH units) sized, unobstructed kidneys with normal cortical thick2 2.28 kPa (4.7–6.0 kPa) ness on ultrasound. Cultures of blood, urine and stool Serum osmolality 334 mosm/kg (280–296 mosm/kg) were all negative for bacteria and parasites. Urine osmolality 404 mosm/kg Urinary sodium 2 mmol/l Haemoglobin, magnesium, amylase and carcinoemUrinary potassium 28 mmol/l bryonic antigen were normal. He was rehydrated with potassium-containing crystalloid to euvolaemia. His