Malabsorption Syndromes

Malabsorption is a failure of digestion, mucosal uptake, or usable intestinal surface—not simply a cause of chronic diarrhea. Three mechanisms organize the clinical picture: luminal maldigestion, as with exocrine pancreatic insufficiency or bile-salt deficiency; mucosal absorptive disease, as with celiac disease; and reduced absorptive surface or abnormal transit, as with short bowel syndrome or small intestinal bacterial overgrowth. The mechanism predicts what the nurse notices first and which test is useful. Greasy, bulky, pale stools suggest impaired fat handling; progressive weight loss and deficiency anemia suggest inadequate nutrient uptake; high-volume diarrhea after bowel resection points toward fluid and electrolyte loss from limited intestinal reserve. Before focusing on the cause, assess perfusion, urine output, mental status, orthostatic symptoms, stool volume, and weight trajectory. The distribution of absorptive work across the small bowel then helps explain the deficiency pattern and directs the diagnostic plan.