Malabsorption Syndromes

Excerpt

The gastrointestinal tract plays a crucial role in absorbing essential nutrients, including 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 intestinal brush border. Although malabsorption and maldigestion differ, digestion and absorption are interdependent, and the term “malabsorption” often refers to either process of this interdependence.

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 gastrointestinal motility (decreased peristalsis and stasis), disrupted bacterial flora, infection, 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, where a large surface area is provided by villi and microvilli and space within the lumen. Additional contributors to digestion and absorption include the gallbladder, pancreas, blood vessels, and lymphatics, each of which has a direct relationship 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 the intestinal microbiome. Presenting symptoms of malabsorption syndromes overlap and include some combination of diarrhea, steatorrhea, unintentional weight loss, and developmental delay or skeletal deformities in children. Due to the various causes of malabsorption syndromes, treatment and symptom management depend on the etiology.