The main purpose of the GI tract is to digest and absorb nutrients (fat, carbohydrate, and 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[3].
It can present in variety of ways and features might give clue to underlying condition. Symptoms can be intestinal or extra-intestinal, 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. Latter also result in bloating, flatulence and abdominal discomfort. Cramping pain usually suggest obstructive intestinal segment e.g. in Crohn's disease especially if persists after defecation.[3]
Weight loss can be significant despite increased oral intake of nutrients[6].
Growth retardation, failure to thrive, delayed puberty in children
There is no specific test for Malabsorption. As for most medical conditions, investigation is guided by symptoms and signs. Moreover, tests for pancreatic function are complex and varies widely between centres.
Blood Tests
Routine blood tests may reveal anaemia, high ESR or low albumin; which has high sensitivity for presence of organic disease [7][8]. In this setting, microcytic anaemia usually implies iron deficiency and macrocytosis can be from impaired folic acid or B12 absorption or both. Low cholesterol or triglyceride may give clue toward fat malabsorption as low calcium and phosphate toward osteomalacia from low vitamin D.
Specific vitamins like vitamin D or micro nutrient like zinc levels can be checked. Fat soluble vitamins (A, D, E & K) are affected in fat malabsorption. Prolonged prothrombin time can be from vitamin K deficiency.
Serological studies
Specific tests are carried out to determine underlying cause.
D-xylose absorption test. lower level in urine after ingestion indicates bacterial overgrowth or reduced absorptive surface. normal in pancreatic insufficiency.
Bile salt breath test to determine bile salt malabsorption.
Treatment is directed largely towards management of underlying cause.
Replacement of nutrients, electrolytes and fluid may be necessary. In severe defeciency hospital admission may be required for parentral administration, often advice from dietician is sought. People whose absortive surface are severely limited from disease or surgery may need long term total parenteral nutrition. Pancreatic enzymes are supplemented orally in insuffeciencies.
Dietary modification is important in some conditions. Life long avoidance of particular food or food constituent may be needed in Celiac disease or lactose intolerence.
Bacterial overgrowth usually respond well to course of antibiotic. Use of cholestyramine to bind bile acid will help reducing diarrhoea in bile acid malabsorption.
^ Jensen, Jonathan E. Malabsorption Syndromes - Page 1. Colorado center for digestive disorders. Retrieved on 2007-05-10.
^ 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, 123-130. ISBN 88-85037-75-5.
^ 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. PMID 12192177.
^ M. S Losowsky,. Malabsorption in clinical practice. Edinburgh: Churchill Livingstone. ISBN 0-443-01007-2.
^ health a to zMalabsorption syndrome. Retrieved on 2007-05-10.
^ 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. PMID 1744388.
^ Read N, Krejs G, Read M, Santa Ana C, Morawski S, Fordtran J (1980). "Chronic diarrhea of unknown origin". Gastroenterology78 (2): 264-71. PMID 7350049.
^ Thomas P, Forbes A, Green J, Howdle P, Long R, Playford R, Sheridan M, Stevens R, Valori R, Walters J, Addison G, Hill P, Brydon G (2003). "Guidelines for the investigation of chronic diarrhoea, 2nd edition". Gut52 Suppl 5: v1-15. PMID 12801941.[1].
