Ingestion of osmotically active substance causes osmotic diarrhoea. Which of the following can cause osmotic diarrhea?

An increased osmotic gap (> 125 mosm/kg) of stool implies that the diarrhea is caused by ingestion or malabsorption of an osmotically active substance. The most common causes of osmotic diarrhea are, Carbohydrate malabsorption due to acquired or congenital defects in brush-border disaccharidases and other enzymes (lactose, fructose, sorbitol) Laxative abuse Malabsorption syndromes (small mucosal intestinal diseases, intestinal resections, lymphatic obstruction, small intestinal bacterial overgrowth, and pancreatic insufficiency) Secretory diarrhea is caused by increased intestinal secretion or decreased absorption resulting in a high-volume watery diarrhea with a normal osmotic gap. Causes include: Endocrine tumors (stimulating intestinal or pancreatic secretion) Bile salt malabsorption (stimulating colonic secretion) Laxatives like castor oil, bisacodyl, and phenolphthalein Ref: McQuaid K.R. (2013). Chapter 15. Gastrointestinal Disorders. In M.A. Papadakis, S.J. McPhee, M.W. Rabow (Eds), CURRENT Medical Diagnosis & Treatment 2013.