Deficient food absorption by the intestinal wall, caused either by the fact that large protein, fat and carbohydrate molecules are not broken down into smaller components which can be absorbed easily (maldigestion), or that the components are produced but cannot pass through the intestinal mucous membrane (resorption deficiency). Many intestinal conditions can lead to malabsorption. Digestive disorders can be caused by conditions of the pancreas (such as mucoviscosidosis, with a characteristic shortage of pancreatic enzymes) or conditions of the liver or bile ducts (shortage of bile salts). Resorption difficulties can be caused by surgical removal of a large section of the small intestine, damage to the mucous membrane (by thrush, for example) or inflammation such as Crohn’s disease, or by parasites or bacteria, malignant diseases, reduced intestinal blood supply, lymph supply disorders, and various others. The following symptoms are produced if the food is not properly digested, but then absorbed: diarrhoea containing fat, loss of weight, distended abdomen and anaemia. There may also be symptoms of the underlying disorder, such as pain caused by pancreatitis, for example. Laboratory tests will show anaemia and a shortage of minerals, proteins and vitamins; tests should also be made to establish the nature of the underlying disorder, unless it it obvious (e.g. signs of chronic pancreatitis found on examining an intestinal sample). A biopsy may be taken from the mucous membrane of the small intestine; other possible tests are contrast X-rays, and examination of the faeces for undigested matter.