What Are Causes of Diarrhea?

Patient Presentation
A 3-year-old male came to clinic with a 6-week history of large, unformed stools at least 4 times/week. Occasionally he will have a formed stool though. The family denies blood, mucous, constipation, excessive juice or fluid intake, or recent antibiotic use. The past medical history showed Clostridium difficile infection 6 months previously after several antibiotic courses, and it was successfully treated with Flagyl®. The family history was positive for an aunt with irritable bowel syndrome. The review of systems was negative.

The pertinent physical exam showed a smiling male with appropriate weight gain since last visit and growth parameters in the 50-90%. The physical examination was negative including all mucous membranes and skin. The diagnosis of chronic diarrhea was made. Stool ova and parasites, bacterial culture, shiga and clostridium toxins were performed and were negative. The patient’s clinical course showed at one week the diarrhea continued and an evaluation for inflammatory bowel disease was begun. At two weeks, the inflammatory bowel disease evaluation was negative and the diarrhea had resolved. The clinician suspected Toddler’s diarrhea despite the negative history.

Diarrhea is increased stool volume, usually with looser consistency and increased frequency than normal. Frequency may not change however. These qualitative attributes are relative to the person’s normal bowel pattern. Acute viral gastroenteritis, one of the most common causes, usually resolves in 2-5 days. Chronic diarrhea is defined as diarrhea lasting more than 2 weeks. With chronic diarrhea there is often a cycle of infection, malabsorption and malnutrition which propagates the diarrhea.

Osmotic diarrhea usually will cease once the offending agent is stopped such as juice (Toddler’s diarrhea) or dairy products (Lactose intolerance). It has a low stool electrolyte content. Weight loss and failure to thrive may be seen. Secretory diarrhea will continue even when taking nothing by mouth. It has a high stool electrolyte content. Infectious diarrhea often is accompanied by fever, nausea, emesis, prior antibiotic use and possibly bloody stools. More commonly it is an acute problem. Inflammatory diarrhea is generally chronic with other signs of disease such as failure to thrive, arthritis, perianal lesions, and/or rash.

Diarrhea prevention includes high standards of hygiene include water, food and personal hygiene. Vaccination against Rotavirus is available in many countries. Treatment for acute diarrhea includes oral rehydration solutions, intravenous isotonic fluids, and early refeeding. Antimicrobials for identified microorganisms depends on the organism and presenting problems. Treatment for chronic diarrhea includes removal of the offending agent (e.g. cow’s milk, laxative, juice, etc.), and appropriate evaluation to identify the disease process and its treatment.

Learning Point
Common causes of diarrhea include:


    • Allergic enteritis – cow’s milk allergy, soy allergy
    • Brush border deficiency – Fructose, Isomaltose, Lactose, Sucrose
    • Infectious
      • Bacteria – common organisms include Aeromonas, Campylobacter, Clostridium, E. coli, Klebsiella, Plesiomonas, Salmonella, Shigella, Vibrio cholera, Yersinia
      • Parasite – common organisms include Amoeba, Cryptosporidium, Giardia, Strongyloides
      • Viral – common organisms include Adenovirus, Astrovirus, Calcivirus, Norovirus, Rotavirus
    • Medications – laxative use or abuse, Magnesium-containing antacids, opioid withdrawal, medication colorants and flavorings such as sorbitol
    • Methylxanthines – caffeine, theophylline
    • Surgical problems – Ascites, Appendicitis, Intussception, Malrotation, Necrotizing enterocolitis, Peritonitis
  • Chronic
    • Abetalipoproteinemia
    • Allergic enteritis – cow’s milk allergy, soy allergy, eosinophilic enteritis
    • Bile salt malabsorption
    • Brush border deficiency – Fructose, Isomaltose, Lactose, Sucrose
    • Celiac disease
    • Congenital chloride diarrhea
    • Endocrine – Addison’s disease, diabetes, hypoparathyroidism, pancreatic insufficiency (Cystic fibrosis, Schwachman-Diamond syndrome), thyrotoxicosis
    • Fecal impaction – including Hirshsprung disease
    • Infectious
      • Parasites – common organisms include Cryptosporidium, Giardia, Tuberculosis
      • Viruses – common organisms include HIV
    • Intestinal lymphangectasia
    • Inflammatory bowel syndrome
    • Immunodeficiency – Common variable immunodeficiency, Graft-vs-Host Disease
    • Irritable bowel syndrome
    • Liver disease, advanced
    • Malnutrition – failure to thrive, acrodermatitis entropathica
    • Medications – alcohol, laxative use or abuse, medication colorants and flavorings such as sorbitol, NSAID enteritis
    • Oncological – primary tumors (including lymphoma), radiation enteritis
    • Psychological – secondary to stress
    • Protein losing enteropathy
    • Surgical problems – short gut syndrome, feeding tube problems
    • Toddler’s diarrhea – excessive intake of clear, sweet liquids
    • Tropical sprue
    • Vitamin
      • Deficiency – Folate, Niacin
      • Toxicity – Niacin

A differential diagnosis of gastrointestinal bleeding can be found here, and one of different colored stools can be found here.

Questions for Further Discussion
1. What is the mathematical formula for determining secretory versus osmotic diarrhea?
2. How common are pediatric diarrheal deaths in the world? In your own country?
3. What is your approach to evaluating chronic diarrhea?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Diarrhea
and at Pediatric Common Questions, Quick Answers for this topic: Chronic Diarrhea

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Lo CW, Walker WA. Chronic Protracted Diarrhea of Infancy: A Nutritional Disease. Pediatrics 1983; 72: 786-800.

Illingworth RS. Common Symptoms of Disease in Children. Blackwell Scientific Publications: Oxford. 1988:90-94.

Woodhead JC. Pediatric Clerkship Guide. Mosby. St. Louis MO, 2003:226-229.

Berkowitz CD. Diarrhea. Pediatrics A Primary Care Approach. W.B. Saunders Company, Philadelphia PA. 1996;344-348.

Grimwood K, Forbes DA. Acute and persistent diarrhea. Pediatr Clin North Am. 2009 Dec;56(6):1343-61.

Guandalini S. Frye RE, Tamer MA. Diarrhea. eMedicine.
Available from the Internet at http://emedicine.medscape.com/article/928598-overview (rev. 4/8/10, cited 10/5/10).

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    5. Patients and their families are counseled and educated.
    7. All medical and invasive procedures considered essential for the area of practice are competently performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.

  • Systems Based Practice
    23. Differing types of medical practice and delivery systems including methods of controlling health care costs and allocating resources are known.
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.


    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa Children’s Hospital