Secretory diarrhoea with high faecal potassium concentrations: a new mechanism of diarrhoea associated with colonic pseudo-obstruction? Report of five patients.

ABSTRACT

OBJECTIVE: To report the mechanism of diarrhoea in patients with subacute colonic pseudo-obstruction, profuse secretory diarrhoea and hypokalemia. PATIENTS Five consecutive patients who developed colonic pseudo-obstruction, profuse watery diarrhoea and severe hypokalemia. Investigations excluded mechanical intestinal obstruction. Usual cause of diarrhoea were ruled out. Abdominal distension and diarrhoea improved simultaneously in all cases after colonoscopic decompression or intravenous neostigmine. RESULTS: Faecal ionograms showed a low osmotic gap and high faecal potassium concentration explaining the hypokalemia 100 to 180 mEq/kg (usually inferior than 50 mEq/l in case of secretory diarrhoea) and low faecal sodium concentrations. Potassium salts were the only factor identified as the driving osmotic force for the diarrhoea. CONCLUSION: Secretory diarrhoea is classically due to chloride active secretion with passive sodium secretion or to inhibition of sodium absorption. In five cases of Ogilvie's syndrome we evidenced an original mechanism of secretory diarrhoea due to active potassium secretion responsible of a profound hypokalemia. This novel type of diarrhoea may be a hallmark of colonic pseudo-obstruction due to colonic distension.