Page 34 - To keep a balance in disease specific intestinal insufficiency. Diagnostics and practical nutritional aspects - Nicolette Wierdsma

Chapter 3
cells separating corporal inside from external environment, i.e. the intestinal contents. By maintaining an intact (electively-permeable) intestinal barrier membrane, pathogenic organisms will be prevented to translocate from the lumen into the body. This is a highly regulated system with inborn and adaptive immune systems which constitutes a complex network of immunoglobulin, mucus, defensins, and other antimicrobial products (3).
Pathophysiology
A wide array of diseases may alter intestinal physiology, which may result in intestinal dysfunction like maldigestion, malabsorption, dysmotility, malassimilation or increase in intestinal permeability (and, hence, decrease in immune defense). It may therefore induce clinically relevant pathophysiological symptoms like diarrhea or constipation, nausea or vomiting, anorexia, pain, bloating and increased abdominal gas production (eructation, flatulence), heartburn, weight loss, micronutrient deficiencies, impaired immune defense, disbalance of intestinal microbiome, and even life-threatening sepsis. This symptomatology may precede or predict malnutrition secondarily to inadequate nutrient intake, nutrient losses or an accelerated -usually catabolic- metabolism. Maldigestion, defined as an exocrine digestive organ dysfunction leading to insufficient digestion, may occur due to reconstructive or exciding surgery, intestinal fistulas, inflammation (e.g. exocrine pancreatic insufficiency in chronic pancreatitis), decreased gastrointestinal transit time (hypermotility), enterocyte dysfunction (or reduced functional intestinal mass) with subsequent absence of brush border enzymes (like in celiac disease). Maldigestion may be primarily or secondarily, and temporary or chronic by nature. As a consequence, GI complaints and malabsorption may occur.
Malabsorption is defined as a inadequate intestinal absorption of fluid and nutrients. It can occur from diseases that affect the bowels integrity, such as inflammatory diseases of the GI tract (such as Crohn’s disease), Whipple’s disease, celiac disease, oncological treatment (chemotherapy or radiotherapy), or in Intensive Care Unit (ICU) due to Multiple Organ Dysfunction Syndrome, and many others. Malabsorption has been associated with impaired clinical outcomes, such as higher mortality rates, longer hospitalization (for instance ICU) stay and mechanical ventilation, increased morbidity and healthcare costs (4). In parallel to nutrient malabsorption, absorption of medication may also be impaired. Therefore, drug dosage sometimes has to be adapted.
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