Common Causes of Non-Bloody, Chronic Diarrhea: Inadequate Weight Gain
Note: This list is not exhaustive |
Diagnosis
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Clinical Features
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Laboratory/Imagining Testing
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Initial Management
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Inflammatory bowel disease (IBD)
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- Possible blood in stool (blood is more common in colitis)
- Stooling urgency and frequency
- Nocturnal stools
- Abdominal pain
- Fatigue
- Weight loss
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- ESR and CRP elevation
- CBC: Iron deficiency anemia, reactive thrombocytosis
- CMP: Hypoalbuminemia, electrolyte abnormalities
- Fecal calprotectin elevated (often > 250 µg/g)
- Infectious stool studies negative
- Imaging may show bowel wall thickening
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- Consider PRBC transfusion if Hgb <7 g/dL or <8 g/dL with symptoms (fatigue, dizziness, tachycardia)
- IVF if signs of dehydration or significant diarrhea
- Pain management: avoid opioids and NSAIDs; prefer acetaminophen as needed
- Consult GI specialists for EGD/colonoscopy with biopsies to confirm diagnosis and provide further management
- Treatment may involve corticosteroids and/or immunosuppressants
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Food protein-induced allergic proctocolitis (FPIAP)
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- Most common triggers are cow’s milk and soy proteins
- May have diarrhea (+/- blood), vomiting, and growth failure
- Often presents within the first few months of life but can persist up to age 3
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- Diagnosed clinically; labs and imaging are generally not needed
- Guaiac fecal occult blood test (gFOBT) may be positive
- CBC: Possible iron deficiency anemia
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- IV fluids if signs of dehydration or significant diarrhea
- Dietary elimination of cow’s milk +/- soy (for at least 2 weeks)
- Consider hydrolyzed or elemental formula
- Consider Nutrition consult
- Generally resolves by 1-2 years of age. Consider rechallenge of food protein ~1 year of age.
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Celiac disease
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- Various presenting symptoms including abdominal distension, constipation or diarrhea, rashes, joint pain, headaches
- Weight loss or poor weight gain
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- Anti-Tissue Transglutaminase IgA (tTG-IgA) diagnostic algorithm (must be eating a gluten-containing diet for accurate results)
- Total serum IgA (may be deficient)
- Elevated tTG IgA, +/- positive antiendomysial IgA antibodies
- If under 2 years old or IgA deficient: elevated deaminated gliadin peptide (DGP) IgG
- Duodenal biopsy histology for confirmation: Villous blunting and intraepithelial lymphocytes
- HLA genetic testing (HLA-DQ2/DQ8) not necessary unless testing is inconclusive (negative HLA DQ2/DQ8 rules out celiac disease)
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- Consult GI specialists for EGD with biopsies to confirm diagnosis (must be eating a gluten-containing diet for accurate results)
- Treatment is a lifelong strict gluten-free diet; recommend establishing with a multidisciplinary team including a GI specialist and Nutrition for initial education and monitoring
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Immunodeficiency
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- Recurrent infections
- Often presents in infancy
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- Immunoglobulin testing: Low IgG, low IgA, high IgM
- CBC: Lymphopenia
- Low antigen titers to previous immunizations
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- Consider referral to Immunology specialists for further evaluation and treatment of primary immunodeficiency
- Supportive care
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Autoimmune enteropathy
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- Rare cause of refractory secretory diarrhea
- Protein losing enteropathy
- Typically associated with severe weight loss and malnutrition
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- Serum antienterocyte, antigoblet cell, anticolonocyte antibodies may be positive
- Serum hypoalbuminemia and positive fecal alpha 1 antitrypsin (A1AT)
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- Consult GI specialists for further evaluation, potential confirmatory endoscopy, and management
- May require parenteral nutrition
- Long term treatment may involve corticosteroids +/- immunosuppressives
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Cystic fibrosis
(Exocrine pancreatic insufficiency/EPI)
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- Malabsorption of carbohydrates, fats, and protein
- Weight loss
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- Newborn screen positive
- Elevated sweat chloride test
- Elevated fecal fat, low fecal elastase (<200 mcg/g)
- Direct pancreatic function test can be done to confirm EPI
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- Consult Pulmonology and GI specialists, Nutrition
- Initiate pancreatic enzyme replacement therapy (PERT) - dosing recommendations can be provided by Pharmacy
- Supplement fat-soluble vitamins (A, D, E, and K)
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References:
1. Zella GC, Israel EJ. Chronic diarrhea in children. Pediatr Rev. 2012;33(5):207-218.
2. Mallon D, Hajjat T. Serologic evaluation of celiac disease for patients younger than 2 years of age. J Pediatr. 2020;224:16-17.
3. Martin MG, Thiagarajah JR. Approach to chronic diarrhea in children >6 months in resource-abundant settings. In: Connor RF, ed. UpToDate. Wolters Kluwer. Accessed May 2026
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