Malabsorption Syndromes

Excerpt

The gastrointestinal tract is involved in absorbing nutrients such as fats, carbohydrates, proteins, vitamins, minerals, and trace elements. Malabsorption refers to impaired nutrient absorption at any point where nutrients are absorbed, and maldigestion refers to impaired nutrient digestion within the intestinal lumen or at the brush border. Although malabsorption and maldigestion differ, digestion and absorption are interdependent. Therefore, in much literature, the term “malabsorption” refers to either process of this interdependence. For this discussion, the malabsorption syndromes addressed will primarily refer to those arising from dysfunction at the level of the small intestine, pancreas, or gallbladder.

Malabsorption can arise from any defect in the digestion/absorption process. These defects can result from an inherent disease of the mucosa, conditions that lead to acquired damage of the mucosa, congenital defects in the intestinal membrane transport systems, impaired absorption of specific nutrients, impaired GI motility (decreased peristalsis and stasis), disrupted bacterial flora, infection, or compromised blood flow or compromised lymphatics. The result is either a global impairment of absorption of all nutrients or specific nutrients.

Impaired nutrient absorption is often located somewhere along the small intestine since it provides a substantial surface area maximized by villi and microvilli and space within the lumen. Additional contributors to digestion and absorption are the gall bladder, pancreas, blood vessels, and lymphatics, each having direct relationships with the small intestine. Digestion and absorption occur by a combination of mechanical mixing, enzyme synthesis, enzyme secretion, enzymatic activity, mucosal integrity, blood supply, intestinal motility, and a balanced microbial flora. Presenting symptoms of malabsorption syndromes overlap and some combination of diarrhea, steatorrhea, unintentional weight loss, developmental delay or skeletal deformities (in children), and, in many cases, observable anemia. Because of the various causes of malabsorption syndromes, treatment course and symptom management depend on etiology. This article will address digestion, absorption, and multiple malabsorption syndromes but will not be all-inclusive.