[Gastrointestinal causes of weight loss: clinical presentation, diagnostic workup and therapy]

This review describes the gasterointestinal entities, their pathophysiology, clinical presentation, diagnostic workup and therapy that typically involve weight loss as the major presenting symptom. The differentiation of malassimilation into maldigestion and malabsorption is clinically mostly not helpful. Instead primary malasssimilation can be distinguished from secondary due to another disease. Celiac disease, lambliasis, small bowel CD, CVIDS and Whipple's disease result in loss of absorptive surface. Chronic intestinal pseudobstruction leads to weight loss through dysmotility and postprandial pain. Microscopic colitis involves some weight loss and needs to be considered because of its high prevalence. Exocrine pancreatic insufficiency and the various protein loosing enteropathies may be primary or secondary syndromes. Dumping, bile acid malabsorption and short bowel syndrome occur after typical operative procedures. Chronic radiation enteritis, chronic intestinal ischemia and intestinal diabetic polyneuropathy are due to chronic intestinal injury.