The pathology of malnutrition and malabsorption

Adequate nutrition depends on the ingestion of a suitable diet and its proper digestion, absorption and metabolism. Malnutrition can result from inadequacy of one or more of these functions. Protein-calorie malnutrition results from severe dietary protein deficiency and is largely a problem in developing countries, with the highest prevalence in south-central Asia and Sub-Saharan Africa. The proximal small intestine is the principal site of nutrient absorption, so, not surprisingly, most malabsorption disorders result from disease of this site. Upper gastrointestinal tract endoscopy is a routine investigation for malabsorption, potentially providing tissue for histopathology, biochemical samples for disaccharidase levels and jejunal fluid for microbial culture. Gluten sensitivity affecting non-enteric sites is primarily manifest as an intra-epithelial lymphocytosis. The endoscopic features of gluten-induced enteropathy include a reduction in the number of circular folds, scalloping of folds, mucosal fissures and a mosaic or nodular mucosa.