2
Overview and Prevalence
Key Point
• Malabsorptive diarrhea is most commonly related to malabsorption of fat.
Prevalence of Target Diseases
• Diarrhea in non-hospitalized patients is common, affecting as much as 5%
of the population. In the context of concurrent alarm signs (weight loss and
vitamin deficiency in particular) and an underlying diagnosis involving the
gastrointestinal (GI) tract, malabsorption should be considered.
• Diarrhea associated with hospitalization is common and may occur in up to
12-32% of patients. This can be due to a multitude of causes and frequently
relates to medication side effects.
▶ Diarrhea is often incorrectly implicated as a side effect of enteral nutrition and
may result in inadequate nutrition support for hospitalized patients.
• In critically ill patients, malabsorption can be associated with fat or
carbohydrate; however, it is unknown if this is long-standing or clinically
important.
▶ Fat malabsorption: Critical illness itself has been implicated in malabsorption
associated directly with critically ill patients (e.g. septic shock). However,
malabsorption may also occur for many reasons in less acutely ill patients.
› Some studies have suggested that as many as 50% of patients have relative
pancreatic insufficiency during the course of critical illness.
› Irregularities of bile salt secretion may also contribute.
▶ Carbohydrate malabsorption: This may occur due to downregulation of active
transporters along the mucosal brush border. This is often a less clear contributor
than fat malabsorption.
• When considering malabsorption as a cause of diarrhea, have a rational
thought process for evaluating the GI tract (Table 1) and potential causes of
fat malabsorption (Table 2).
Abbreviations
ELISA, enzyme-linked immunosorbent assay; EN, e nteral nutrition; EPI, exocrine
pancreatic insufficiency; FDA, Food and Drug Administration; FE, Fecal Elastase; GI,
gastrointestinal; IBD, Inflammatory bowel diseases; MCT, medium chain triglycerides;
mEq, milliequivalent; Na, sodium; NPO, nil per os; PERT, pancreatic enzyme
replacement therapy
