What is the diagnosis and treatment for a patient presenting with steatorrhea (pasty stool)?

Understanding Pasty Stool (Steatorrhea)

Definition and Clinical Significance

Pasty stool alone is a nonspecific symptom that does NOT reliably indicate fat malabsorption or steatorrhea. 1, 2 True steatorrhea presents with bulky, pale/light-colored, malodorous stools that obviously float due to high fat content, typically requiring >7% of ingested fat in stool or a coefficient of fat absorption <93%. 2, 3

The World Health Organization defines normal diarrhea as passage of 3 or more loose or liquid stools per 24 hours, but specifically notes that frequent passing of loose, "pasty" stools by infants consuming human milk is not diarrhea. 1 This distinction is critical—pasty consistency alone, without other features of steatorrhea, should not trigger an extensive malabsorption workup.

Key Diagnostic Features to Distinguish True Steatorrhea

Characteristics of True Steatorrhea

• Bulky, pale/light-colored stools that are obviously malodorous and float 2, 3
• Visible oil in stool (indicates severe or decompensated pancreatic exocrine insufficiency) 2
• Associated symptoms: flatulence, bloating, dyspepsia, urgency, cramping abdominal pain 3
• Weight loss despite adequate caloric intake 3
• Fat-soluble vitamin deficiencies (A, D, E, K) even in mild-moderate cases 3

When Pasty Stool is NOT Steatorrhea

• Floating stools from gas are physiologically normal and related to swallowed air or bacterial fermentation 3
• Temporary floating without other features of malabsorption 3
• Nonspecific symptoms like bloating, excess gas, and foul-smelling stools that may respond to various treatments but represent placebo effect 2, 3

Critical Pitfall to Avoid

The American Gastroenterological Association strongly recommends against initiating empiric pancreatic enzyme replacement therapy (PERT) without appropriate diagnostic testing. 2 Symptomatic improvement may represent placebo effect and mask other disorders like celiac disease, causing delays in correct diagnosis. 2, 3

Diagnostic Approach

Initial Evaluation

A complete history focusing on specific features is essential: 2

• Weight loss (unintentional) 3
• Dietary history and relationship of symptoms to meals 2
• Risk factors for pancreatic disease: chronic pancreatitis, pancreatic surgery, alcohol use, diabetes, cystic fibrosis 4
• Prior cholecystectomy (suggests bile acid malabsorption) 1
• Nocturnal diarrhea (suggests organic pathology) 1

Physical Examination

• Signs of malnutrition or vitamin deficiency 2
• Abdominal masses or organomegaly 2

Laboratory Testing Algorithm

First-line blood tests: 1, 2

• Complete blood count 1
• C-reactive protein or erythrocyte sedimentation rate 1
• Celiac serology (tissue transglutaminase IgA and total IgA) 1, 3
• Albumin 2
• Fat-soluble vitamin levels (A, D, E, K) if malabsorption suspected 3

Stool testing: 1, 2

• Stool for occult blood 2
• Fecal calprotectin in patients <45 years with diarrhea to exclude inflammatory bowel disease 1
• Fecal elastase-1 (FE-1) if clinical features suggest true malabsorption 2, 3, 4
  • FE-1 <100 μg/g provides good evidence of exocrine pancreatic insufficiency (EPI) 3, 4
  • FE-1 100-200 μg/g is indeterminate 3, 4
  • FE-1 >200 μg/g is normal 3, 4
  • Must be performed on semi-solid or solid stool (liquid stool gives false positives) 4

Infectious workup if indicated: 1

• Clostridioides difficile testing 1
• Stool cultures or pathogen panels 1
• Ova and parasite testing based on risk factors 1

When to Perform Advanced Testing

Cross-sectional imaging (CT, MRI, or endoscopic ultrasound): 3, 4

• If FE-1 suggests pancreatic insufficiency 3
• High clinical suspicion for chronic pancreatitis or pancreatic carcinoma 3
• Cannot diagnose EPI but identifies underlying pancreatic pathology 4

Upper endoscopy with distal duodenal biopsies: 3

• If celiac serology is positive 3
• If FE-1 is normal but steatorrhea persists 3
• To diagnose celiac disease or other small bowel enteropathies 3

SeHCAT testing or therapeutic trial of cholestyramine: 1, 3

• For bile acid malabsorption, especially with prior cholecystectomy or nocturnal diarrhea 1
• SeHCAT testing is sensitive but not widely available 3
• Therapeutic trial of cholestyramine is reasonable alternative 3

Quantitative fecal fat testing: 1, 3

• Rarely needed and generally not practical for routine use 3, 4
• Consider only when clinical features are inconclusive or assessing inadequate response to PERT 4
• Requires diet of known fat content over 5 days with stool collection during final 3 days 3
• Fecal fat >13 g/day (47 mmol/day) indicates severe steatorrhea 1, 3

Common Causes and Their Management

Exocrine Pancreatic Insufficiency (EPI)

Most common cause of severe steatorrhea (fecal fat >13 g/day). 1, 3 Requires >90% pancreatic destruction before symptoms become evident. 1

Treatment with PERT: 4, 5

• Initial dosing: 40,000 USP units of lipase during each meal, 20,000 units with snacks 4
• Take during meals, not before or after 4, 5
• Swallow capsules whole; if unable, sprinkle contents on acidic soft food (pH ≤4.5) like applesauce 5
• All formulations are porcine-derived and equally effective at equivalent doses 4
• Monitor: reduction in steatorrhea, weight gain, muscle mass improvement, fat-soluble vitamin levels 4
• Dietary modifications: low-moderate fat diet with frequent smaller meals 4
• Routine supplementation and monitoring of fat-soluble vitamins 4

Celiac Disease

Second most common cause of malabsorption. 6 Can present with diarrhea, weight loss, or nonclassic symptoms including anemia, osteoporosis, transaminitis. 7

Diagnosis: 7, 8

• IgA tissue transglutaminase is initial screening test 7
• Esophagogastroduodenoscopy with small bowel biopsy confirms diagnosis 7
• Mucosal pathology ranges from intraepithelial lymphocytosis to completely flat mucosa 8

Treatment: 7

• Gluten-free diet for life 7
• Support groups and education on hidden gluten sources, cross-contamination 7

Bile Acid Malabsorption

Contributes to diarrhea when ≥100 cm of terminal ileum resected. 1

Treatment: 1, 3, 6

• Bile acid sequestrants: cholestyramine, colestipol, or colesevelam 3, 6
• Caution: cholestyramine may increase fat malabsorption by reducing bile salt pool 1

Small Intestinal Bacterial Overgrowth (SIBO)

Can cause steatorrhea and is common complication in patients with EPI. 1, 3

Treatment: 1, 6

• Antibiotics (typically rifaximin) as initial management 6
• Dietary modifications to reduce fermentable carbohydrates 3
• Probiotics and prokinetic drugs as alternatives 6

Short Bowel Syndrome

Patients with preserved colon rarely need water/sodium supplements but have significant diarrhea. 1

Treatment: 1

• Loperamide 2-8 mg given 30 minutes before food 1
• Occasionally codeine phosphate 30-60 mg before food 1
• Cholestyramine if ≥100 cm terminal ileum resected 1
• Parenteral nutrition may be needed to allow reduced oral intake and decreased diarrhea 1

Alternative Diagnoses for Pasty Stool Without Steatorrhea

Irritable Bowel Syndrome (IBS)

Should be considered in patients with pasty stools, bloating, and gas without structural or biochemical abnormalities. 1, 2

Diagnosis: 1

• Positive diagnosis based on symptoms in absence of alarm features 1
• Abdominal pain/discomfort with altered bowel habit for ≥6 months 1

Treatment: 1

• Regular exercise 1
• First-line dietary advice 1
• Soluble fiber (ispaghula) 3-4 g/day, gradually increased 1
• Low FODMAP diet as second-line therapy, supervised by dietitian 1
• Loperamide for diarrhea 1

Dietary Factors

High fiber intake or excess gas production from fermentable carbohydrates can cause pasty, floating stools. 2

Immune Checkpoint Inhibitor Enterocolitis

In patients on cancer immunotherapy, consider ICI-related diarrhea. 1

Workup: 1

• Exclude infectious causes (C. difficile, stool cultures) before immunosuppression 1
• Fecal elastase with adjunctive fecal fat testing for patients with steatorrhea or not responding to typical treatments 1
• Immune-mediated pancreatic insufficiency is uncommon but important cause 1
• Stool inflammatory markers (lactoferrin or calprotectin) help stratify patients 1