A falling row of dominoes

A 60-year-old man presented himself in the emergency room in a state of deep shock and severe metabolic acidosis (pH=6.654). He had an acute abdomen, initially attributed to intestinal ischaemia, based on abdominal pain, CT findings and high blood lactic acid levels (22 mmol/l). At exploratory laparotomy, though, only viable intestines were found. A solid mass at the mesenteric root was biopsied and would later prove to be a carcinoid tumour. This tumour led to chronic diarrhoea, which was attributed to other causes. Slowly and progressively his kidney function diminished, as the tumour further dehydrated him. Not drinking for hours during long- distance travel finally tipped the balance. The resulting hypovolemic shock cannot fully explain the deep acidosis or extremely high lactic acid level, so one final domino is missing...