MRCP2-1857
A 35-year-old man with a history of ulcerative colitis is admitted to the hospital due to worsening symptoms over the past three weeks. He reports passing bloody stools six times a day. After being treated with intravenous steroids for three days, he complains of increasing abdominal pain. During examination, he has diffuse abdominal tenderness with rebound and a pulse of 122 bpm with a temperature of 39.2°C. Blood tests reveal several electrolyte abnormalities, including low potassium and albumin levels. An abdominal x-ray shows a loop of featureless transverse colon with a maximum diameter of 6.8 cm. The patient has been taking increasing doses of ibuprofen to control his pain and has recently undergone an endoscopic examination. According to the 2007 European Crohn’s and Colitis Organisation consensus guidelines on the management of ulcerative colitis, which electrolyte abnormality should be corrected first to prevent further colonic dilatation?