Malabsorption constitutes the pathological interference with the normal physiological sequence of digestion (intraluminal process), absorption (mucosal process) and transport (postmucosal events) of nutrients.
They can occur in a variety of ways and features might give a clue to the underlying condition. Symptoms can be intestinal or extra-intestinal - the former predominates in severe malabsorption.
Diarrhoea, often steatorrhoea, is the most common feature. Watery, diurnal and nocturnal, bulky, frequent stools are the clinical hallmark of overt malabsorption. It 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
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).
Treatment is directed largely towards management of underlying cause:
Replacement of nutrients, electrolytes and fluid may be necessary. In severe deficiency, hospital admission may be required for nutritional support and detailed advice from dietitians. Use of enteral nutrition by naso-gastric or other feeding tubes may be able to provide sufficient nutritional supplementation. Tube placement may also be done by percutaneous endoscopic gastrostomy, or surgical jejunostomy. In patients whose intestinal absorptive surface is severely limited from disease or surgery, long term total parenteral nutrition may be needed.
Pancreatic enzymes are supplemented orally in pancreatic insufficiency.
Dietary modification is important in some conditions:
^Gasbarrini G, Frisono M: Critical evaluation of malabsorption tests; in G. Dobrilla, G. Bertaccini, G. Langman (Editor) (1986). Problems and Controversies in Gastroenterology. New York: Raven Pr. pp. 123–130. ISBN88-85037-75-5.
^Walker-Smith J, Barnard J, Bhutta Z, Heubi J, Reeves Z, Schmitz J (2002). "Chronic diarrhea and malabsorption (including short gut syndrome): Working Group Report of the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition". J. Pediatr. Gastroenterol. Nutr. 35 Suppl 2: S98–105. doi:10.1097/00005176-200208002-00006. PMID12192177.
^M. S Losowsky, (1974). Malabsorption in clinical practice. Edinburgh: Churchill Livingstone. ISBN0-443-01007-2.
^Bertomeu A, Ros E, Barragán V, Sachje L, Navarro S (1991). "Chronic diarrhea with normal stool and colonic examinations: organic or functional?". J. Clin. Gastroenterol.13 (5): 531–6. doi:10.1097/00004836-199110000-00011. PMID1744388.
^Read N, Krejs G, Read M, Santa Ana C, Morawski S, Fordtran J (1980). "Chronic diarrhea of unknown origin". Gastroenterology78 (2): 264–71. PMID7350049.