Malabsorption

Basics

Description

  • Malabsorption is characterized as a syndrome, as opposed to a disease entity, and is defined as any state in which there is a disturbance of digestion and/or absorption of nutrients across the intestinal mucosa.
  • The classical symptoms of malabsorption include chronic diarrhea, abdominal distention, and failure to thrive.
  • Malabsorption is caused by either a congenital or acquired disorder.

Epidemiology

Depends on the underlying disease causing malabsorption

Etiology

The most common causes of malabsorption in developed countries are as follows:

  • Celiac disease: most common inherited malabsorption syndrome; documented prevalence of 1%
  • Cystic fibrosis
  • Post enteritis syndrome
  • Cow’s milk protein intolerance
  • Giardiasis
  • Inflammatory bowel disease (IBD)

Pathophysiology

  • Differs depending upon which nutrient is malabsorbed
    • Carbohydrate
      • Monosaccharide: congenital glucose-galactose deficiency, fructose intolerance
      • Disaccharide: lactase deficiency (congenital or acquired), sucrase-isomaltase deficiency
      • Polysaccharide: amylase deficiency (congenital or acquired)
    • Fat
      • Bile salt deficiency: cholestasis, resection of terminal ileum
      • Exocrine pancreatic insufficiency: cystic fibrosis, chronic pancreatitis
      • Inadequate surface area: celiac disease, flat villous lesions
    • Protein
      • Protein-losing enteropathy: intestinal lymphangiectasia, congenital heart failure
      • Exocrine pancreatic insufficiency: cystic fibrosis, Shwachman-Diamond syndrome
      • Inadequate surface area: celiac disease
  • Differs according to location of alteration in absorptive function of gut
    • Mucosal abnormality
      • Anatomic: postenteritis syndrome, celiac disease, IBD
      • Functional: disaccharidase deficiencies
    • Luminal abnormality
      • Exocrine pancreatic insufficiency: cystic fibrosis, Shwachman-Diamond syndrome
      • Bile salt insufficiency: biliary cholestatic liver disease, ileal resection
    • Anatomic abnormality
      • Short gut: surgical resection
      • Motility disturbance: intestinal pseudo-obstruction

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