Introduction

A 30-year-old woman with long-standing irritable bowel syndrome presented to the emergency department with syncope, on a background of 3 weeks of bloody diarrhoea and 6 kg weight loss. She did not smoke, took only the combined oral contraceptive and reported no recent travel.

Laboratory tests revealed a macrocytic anaemia: Hb 48 g/L mean corpuscular volume 100.8 fL and reticulocytes 115.2 10⁹ /L. Liver function was deranged: bilirubin 31 μmol/L, alanine transaminase 115 U/L aspartate transaminase 150 U/L albumin 23 g/L, international normalized ratio 1.3. C reactive protein 29, and creatine was 90 µmol/L and urea 2.7 mmol/L. Haematinics were normal. She was transfused 2 units of blood, but despite blood transfusion did not significantly increment the Hb, with ongoing bloody diarrhoea. Serum haptoglobin was <0.1 g/L, lactate dehydrogenase 549 and bilirubin 24 µmol/L; direct antiglobulin test (DAT) …