Malabsorption

Malabsorption is impaired nutrient absorption in the small intestine, causing deficiencies and related symptoms. It can be generalized or selective, most often affecting fats. The condition may persist despite adequate intake.

Causes include pancreatic insufficiency (chronic pancreatitis, cystic fibrosis) that impairs digestion; mucosal diseases (celiac disease, Crohn's disease) that reduce absorptive surface; small intestinal bacterial overgrowth (SIBO) and short bowel syndrome; bile acid malabsorption; infections; medications such as orlistat; and post-surgical changes. Malabsorption can involve fat, carbohydrates, proteins, and micronutrients.

Symptoms vary; common signs are chronic diarrhea or steatorrhea, weight loss, bloating, abdominal pain, and fatigue. Deficiencies of fat-soluble vitamins and minerals can cause vision problems, bone disorders, anemia, neuropathy, or edema.

Diagnosis combines history, examination, and tests. Stool fat testing or pancreatic elastase assesses fat digestion; blood tests screen for nutrient deficiencies; serology and biopsy help diagnose mucosal diseases; D-xylose and breath tests detect absorptive defects or SIBO; endoscopy with biopsy is used when indicated.

Management targets the underlying cause and nutritional deficiencies. Dietary adjustments may include fat modification or gluten-free or lactose-free diets depending on the cause. Pancreatic enzyme replacement for pancreatic insufficiency; vitamins and minerals supplementation; antibiotics for SIBO; and surgical options for short bowel syndrome in selected cases. Prognosis depends on cause and treatment response.