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