Skip to content

Chronic Diarrhea

Basics

Description

  • Loose stools (types 5–7, Bristol chart) > 3/day lasting >4 weeks

  • Etiologies: osmotic, secretory, malabsorptive, inflammatory, infectious, hypermotility

Epidemiology

  • Global prevalence: ~3–20%

  • U.S. prevalence: ~6.6%

  • Difficult to estimate incidence due to varying definitions

Etiology & Pathophysiology

Mechanisms

  • Osmotic: fecal osmotic gap >100, resolves with fasting

    • e.g., lactose/fructose/polyol intolerance, magnesium, sulfate, phosphate, carbohydrate malabsorption

  • Secretory: fecal osmotic gap <50, persists with fasting

    • e.g., bile acid diarrhea, neuroendocrine tumors, infections, stimulant laxative use

  • Malabsorptive: high stool volume

    • e.g., celiac, Whipple, tropical sprue, chronic pancreatitis, short bowel syndrome, SIBO

  • Inflammatory: loose, occasionally bloody

    • e.g., IBD, radiation, CMV, E. histolytica

  • Hypermotility: normal osmotic gap

    • e.g., IBS, functional diarrhea

  • Drug-induced: NSAIDs, PPIs, colchicine, SSRIs, etc.

  • Genetic associations:

    • Celiac: HLA-DQ2/DQ8

    • IBD: Polygenic

    • CF: CFTR mutations

Risk Factors

  • Osmotic: sugar alcohols, laxatives, lactose intolerance, celiac

  • Secretory: post-surgical bowel changes, stimulants, neuroendocrine tumors

  • Malabsorptive: CF, alcohol, celiac, pancreatic insufficiency

  • Inflammatory: IBD, HIV, C. difficile, cancer, antibiotics, immunosuppression

  • Hypermotility: IBS, post-infectious, stimulant medications

⚠️ DM and post-cholecystectomy can cause both secretory & osmotic diarrhea

Prevention

  • Etiology-specific, often resolved with management of underlying disease

Associated Conditions

  • IBD: Extraintestinal signs—arthralgia, uveitis, aphthous ulcers, PSC

  • Celiac: Dermatitis herpetiformis, T1DM, IgA deficiency

  • Latex-food syndrome: Allergy to banana, avocado, kiwi, walnut

Diagnosis

History

  • Onset, pattern, stool characteristics (greasy, watery, floating), urgency, family history

  • Alarm symptoms: bleeding, weight loss, fever, nocturnal symptoms, onset >50 yrs

  • Rome IV Criteria:

    • IBS: Recurrent abd pain + ≥2 of: relation to defecation, frequency, form

    • Functional diarrhea: ≥25% loose stools, no pain, duration >6 months

Physical Exam

  • Skin: erythema nodosum, pyoderma gangrenosum, ecchymoses, dermatitis herpetiformis

  • HEENT: uveitis, goiter, oral ulcers

  • CVS: murmurs (carcinoid)

  • Abdomen: hyperactive bowel sounds, tenderness, fistulas

  • Neuro: tremor (hyperthyroid), spondylitis

Initial Tests

  • Labs: CBC, ESR/CRP, albumin, TSH, Fe studies, Ca/Mg/Phos

  • Stool: calprotectin, lactoferrin, C. diff, O&P, Giardia Ag, fecal fat, osmotic gap

  • Imaging: CT/MRI for IBD, malignancy, chronic pancreatitis

Follow-Up/Special Tests

  • Celiac: anti-TTG IgA, total IgA, duodenal biopsy

  • Pancreatic: fecal elastase, chymotrypsin, trypsinogen

  • Protein loss: fecal α1-antitrypsin

  • Microscopic colitis: colon biopsy from normal mucosa

  • Carb malabsorption: stool pH, hydrogen breath test

  • SIBO: breath test, jejunal aspirate

  • Neuroendocrine tumors: chromogranin A, 5-HIAA, CT/MRI

Endoscopy

  • Ileocolonoscopy: IBD, microscopic/CMV colitis, cancer

  • EGD with biopsy: malabsorption, celiac

  • MRCP/MRE: if pancreatitis or small bowel disease suspected

Treatment

General Measures

  • Rehydrate, correct electrolytes, outpatient if stable

First-Line Therapies

  • Lactose intolerance: lactose-free diet

  • Bile acid diarrhea: cholestyramine, colestipol

  • Hyperthyroid: methimazole/PTU

  • Infections:

    • C. diff: vancomycin, metronidazole, fidaxomicin

    • Giardia: metronidazole, nitazoxanide

    • Whipple disease: ceftriaxone IV + Bactrim for 1–2 years

  • SIBO: rifaximin, fluoroquinolones, metronidazole

  • Microscopic colitis: budesonide, mesalamine, bismuth

  • IBD: 5-ASA, corticosteroids, biologics (anti-TNF), immunomodulators

  • Celiac disease: gluten-free diet

  • IBS-D: rifaximin, alosetron, peppermint oil, eluxadoline, TCAs

  • Symptom relief: loperamide, diphenoxylate-atropine, fiber, bismuth

Referral & Surgery

  • Refer to gastroenterology for endoscopy or suspected IBD

  • Surgery: for refractory IBD, neuroendocrine tumors

  • Fecal transplant for recurrent C. difficile

Ongoing Care

Diet

  • Elimination diet: gluten, FODMAPs, lactose, allergens

Patient Education

  • >4 weeks of ≥3 loose stools = chronic diarrhea

  • Dietary triggers and medications often overlooked

Prognosis

  • Depends on cause

  • Excellent with appropriate treatment

Complications

  • Fluid/electrolyte imbalance, AKI, malnutrition, malignancy (IBD, celiac)

References

  1. Schiller LR, et al. Clin Gastroenterol Hepatol. 2017

  2. Chu C, et al. Curr Probl Pediatr Adolesc Health Care. 2020

  3. Burgers K, et al. Am Fam Physician. 2020

  4. Schiller LR. Am J Gastroenterol. 2018

See Also

  • Algorithm: Diarrhea, Chronic

Codes

  • ICD-10: K52.9 – Noninfective gastroenteritis and colitis, unspecified

Clinical Pearls

  • Comprehensive history is key—stool patterns, medication use, family history

  • Alarm symptoms demand thorough workup

  • IBS, IBD, malabsorption, and infections are top differentials

  • Treat underlying cause; avoid blind empirical treatments