is due to impaired water, carbohydrate and electrolyte absorption or irritation from unabsorbed fatty acid. The latter also results in bloating, flatulence and abdominal discomfort. Cramping pain usually suggests obstructive intestinal segment e.g. in Crohn's disease, especially if it persists after defecation. Weight loss can be significant despite increased oral intake of nutrients. Growth retardation, failure to thrive, delayed puberty in children Swelling or oedema from loss of protein Anaemias, commonly from vitamin B12, folic acid and iron deficiency presenting as fatigue and weakness, and the first of which can give rise to neuropsychiatric symptoms such as abnormal sensations, difficulty walking, and decreased mental abilities. Muscle cramp from decreased vitamin D, calcium absorption. Also lead to osteomalacia and osteoporosis Bleeding tendencies from vitamin K and other coagulation factor deficiencies. Causes Pathophysiology The main purpose of the gastrointestinal tract is to digest and absorb nutrients (fat, carbohydrate, protein, micronutrients (vitamins and trace minerals), water, and electrolytes. Digestion involves both mechanical and enzymatic breakdown of food. Mechanical processes include chewing, gastric churning, and the to-and-fro mixing in the small intestine. Enzymatic hydrolysis is initiated by intraluminal processes requiring gastric, pancreatic, and biliary secretions. The final products of digestion are absorbed through the intestinal epithelial cells. Malabsorption constitutes the pathological interference with the normal physiological sequence of digestion (intraluminal process), absorption (mucosal process) and transport (postmucosal events) of nutrients. Intestinal malabsorption can be due to: Congenital or acquired reduction in absorptive surface Defects of ion transport Defects of specific hydrolysis Impaired enterohepatic circulation Mucosal damage (enteropathy) Pancreatic insufficiency Diagnosis There is no single, specific test for malabsorption. As for most medical conditions, investigation is guided by symptoms and signs. A range of different conditions can produce malabsorption and it is necessary to look for each of these specifically. Many tests have been advocated, and some, such as tests for pancreatic function are complex, vary between centers and have not been widely adopted. However, better tests have become available with greater ease of use, better sensitivity and specificity for the causative conditions. Tests are also needed to detect the systemic effects of deficiency of the malabsorbed nutrients (such as anaemia with vitamin B12 malabsorption). Classification Some prefer to classify malabsorption clinically into three basic categories: selective, as seen in lactose malabsorption. partial, as observed in abetalipoproteinaemia. total, as in exceptional cases of coeliac disease. Blood tests Routine blood tests may reveal anaemia, high CRP