Chronic Fatty Diarrhea (Malabsorptive Diarrhea)
Definition: Steatorrhea refers to the passage of pale, bulky, foul-smelling, greasy stools due to fat malabsorption.
Common Causes by Mechanism
1. Gastric Hypersecretion
- Zollinger-Ellison syndrome
- Excess gastric acid inactivates pH-sensitive pancreatic lipases, impairing fat digestion.
2. Medication-Induced Malabsorption
- Orlistat (Xenical) – inhibits pancreatic lipases.
- Acarbose – may cause osmotic diarrhoea and contribute to malabsorption.
3. Proximal Small Bowel Disorders (Impaired Nutrient Absorption)
- Coeliac disease
- Tropical sprue
- Giardiasis
- Whipple’s disease(Tropheryma whipplei)
- Diarrhoea, steatorrhea, weight loss, arthropathy (large joints), fever, CNS involvement.
4. Carbohydrate Malabsorption (May co-exist with steatorrhea)
- Lactose intolerance
- Fructose malabsorption
5. Small Intestinal Infiltrative or Structural Disorders
- Lymphoma
- Amyloidosis
- HIV enteropathy
- Small intestinal bacterial overgrowth (SIBO)
6. Exocrine Pancreatic Insufficiency
- Chronic pancreatitis
- Cystic fibrosis
- Pancreatic duct obstruction (e.g., neoplasm)
- Post-pancreatectomy
7. Bile Acid Deficiency or Malabsorption
- Cholestatic liver diseases:
- Primary biliary cholangitis (PBC)
- Primary sclerosing cholangitis (PSC)
- Distal ileal disease or resection (e.g., Crohn’s disease)
- Reduced bile acid reabsorption → decreased micelle formation.
- SIBO – causes bile acid deconjugation.
Clinical Features
- Pale, bulky, frothy, greasy stools
- Foul-smelling faeces
- Nutritional deficiencies and weight loss
- Flatulence and bloating
- Symptoms improve or resolve during fasting
Diagnostic Work-Up
- Faecal elastase-1 – screening test for pancreatic insufficiency
- Celiac serology – anti-tTG IgA (check total IgA)
- Stool chymotrypsin – alternative pancreatic function test
- Consider:
- Faecal fat quantification (72-hour collection)
- Breath tests for SIBO
- Endoscopy with biopsy (if coeliac or Whipple’s suspected)
- MRCP or CT (if pancreatic or biliary pathology suspected)
Complications
- Malnutrition and weight loss – ↑ infection risk, ↓ healing, ↑ morbidity
- Fat-soluble vitamin deficiencies (A, D, E, K)
- Vitamin D deficiency → osteoporosis, osteopenia, fractures
- Vitamin K deficiency → coagulopathy
- Iron deficiency anaemia (especially in coeliac disease)
- Zinc deficiency – immune dysfunction, poor wound healing
- Megaloblastic anaemia (B12 deficiency from terminal ileum disease or SIBO)
- Coeliac disease-specific complications:
- Dermatitis herpetiformis
- Non-Hodgkin lymphoma
- GI adenocarcinoma
- Chronic pancreatitis sequelae:
- Pancreatic pseudocyst
- Diabetes mellitus
- Splenic vein thrombosis
- Pancreatic cancer