147. Maldigestion and malabsorption syndrome - etiology, pathogenesis, clinical manifestations.

Maldigestion and malabsorption syndrome – etiology, pathogenesis, and clinical manifestations.

Maldigestion: Impaired breakdown of nutrients in the intestinal lumen.

Malabsorption: Impaired uptake of digested nutrients from the intestinal mucosa into blood or lymph.

Often overlap and together referred to as malabsorption syndrome.

Etiology

Maldigestion causes

• Pancreatic insufficiency (chronic pancreatitis, cystic fibrosis) → lack of digestive enzymes.
• Bile acid deficiency (cholestasis, bile duct obstruction) → impaired fat emulsification.
• Defective gastric mixing (e.g., post-gastrectomy).

Malabsorption causes

• Small intestinal mucosal diseases:
• Celiac disease (gluten enteropathy).
• Tropical sprue.
• Crohn's disease.
• Reduced absorptive surface:
• Short bowel syndrome after extensive resections.
• Lymphatic obstruction:
• Intestinal lymphangiectasia, lymphoma.
• Infections:
• Giardia lamblia.
• Whipple’s disease.

Pathogenesis

Maldigestion

1. Insufficient enzymes or bile acids → incomplete breakdown of proteins, carbohydrates, fats.
2. Undigested macromolecules remain in lumen → osmotic diarrhea.
3. Fats unabsorbed → steatorrhea.

Malabsorption

1. Damaged or reduced absorptive mucosa → decreased uptake of nutrients.
2. Specific deficiencies depend on location:

• Proximal small intestine: iron, folate.
• Terminal ileum: vitamin B12, bile acids.

1. 3 Secondary bacterial overgrowth can worsen absorption defects.

Clinical manifestations

General symptoms

• Chronic diarrhea (often bulky, foul- smelling, oily —steatorrhea).
• Abdominal bloating, flatulence.
• Weight loss despite adequate intake.

Nutritional deficiencies