What is steatorrhea?

Steatorrhea: Definition, Diagnosis, and Clinical Implications

Steatorrhea is defined as the presence of excess fat in the stool, clinically manifesting as fatty, foul-smelling, floating stools that are difficult to flush and often associated with symptoms of malabsorption. 1

Pathophysiology and Clinical Features

Steatorrhea occurs when fat malabsorption exceeds normal limits, typically when:

• Fecal fat excretion exceeds 7 g/day (normal is <7 g/day)
• Severe steatorrhea is defined as >13 g/day (47 mmol/day) 1

Clinical Presentation:

• Bulky, pale, greasy, foul-smelling stools that may float
• Often accompanied by:
  • Flatulence
  • Bloating
  • Abdominal pain
  • Urgency to defecate
  • Cramping 1
• May be associated with weight loss and nutritional deficiencies

Common Causes

1. Pancreatic Exocrine Insufficiency (PEI)

• Most frequent cause of severe steatorrhea 1
• Results from insufficient secretion of pancreatic enzymes (particularly lipase)
• Common in:
  • Chronic pancreatitis
  • Pancreatic cancer
  • Post-pancreatic surgery 1
• Symptoms typically develop when pancreatic enzyme secretion is reduced to <10% of normal values 1

2. Small Bowel Disorders

• Celiac disease
• Crohn's disease
• Small intestinal bacterial overgrowth (SIBO)
• Short bowel syndrome 1

3. Biliary Disorders

• Bile acid deficiency
• Biliary obstruction

Diagnostic Approach

Laboratory Testing:

1. Fecal Elastase-1 (FE-1):

   • First-line test for suspected pancreatic exocrine insufficiency
   • Non-invasive and relatively inexpensive
   • High sensitivity (73-100%) and specificity (80-100%) for moderate to severe PEI 2
   • Interpretation:
     • Normal: 200-500 μg/g
     • Mild-moderate insufficiency: 100-200 μg/g
     • Severe insufficiency: <100 μg/g 2

2. Quantitative Fecal Fat:

   • Historically the gold standard but now less commonly used
   • Requires 3-day stool collection
   • Limited by collection difficulties and lack of standardization 1

Imaging:

• Cross-sectional imaging (CT, MRI) to evaluate for underlying pancreatic abnormalities
• MRCP (Magnetic Resonance Cholangiopancreatography) to assess pancreatic and biliary ducts 2

Management

Management depends on the underlying cause but focuses on:

1. For Pancreatic Exocrine Insufficiency:

   • Pancreatic Enzyme Replacement Therapy (PERT):
     • pH-sensitive, enteric-coated microspheres are preferred 1
     • Dosing should be sufficient to normalize digestion
     • Typically administered with meals 1, 3

2. Dietary Modifications:

   • Adequate protein intake
   • Balanced diet with appropriate fat content based on severity
   • In severe cases, MCT (medium-chain triglyceride) oils may be beneficial 1, 4

3. Nutritional Supplementation:

   • Fat-soluble vitamins (A, D, E, K)
   • Minerals (zinc, magnesium) 1

Special Considerations

• Post-Bariatric Surgery: Up to 40% of patients may experience diarrhea post-surgery, with some developing steatorrhea due to fat malabsorption 1

• Visual Assessment: While experienced clinicians may be able to identify steatorrhea visually (sensitivity 89.3%, specificity 91.1%), laboratory confirmation is recommended for accurate diagnosis 5

• False Positives: Liquid stool samples can lead to false positive results in fecal elastase testing 2

By properly identifying and treating steatorrhea, clinicians can prevent malnutrition-related morbidity and mortality and improve patients' quality of life.