Differential Diagnosis for Chronic Diarrhea

Chronic diarrhea is a symptom that can be caused by a wide range of conditions. The differential diagnosis can be organized into the following categories:

• Single Most Likely Diagnosis

  • Irritable Bowel Syndrome (IBS): This is often considered the most likely diagnosis for chronic diarrhea due to its high prevalence and the fact that it can present with a variety of gastrointestinal symptoms, including chronic diarrhea, without an identifiable cause.

• Other Likely Diagnoses

  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic diarrhea, along with other symptoms such as abdominal pain and weight loss.
  • Lactose Intolerance: The inability to digest lactose, a sugar found in milk and other dairy products, can lead to chronic diarrhea in some individuals.
  • Small Intestine Bacterial Overgrowth (SIBO): An overgrowth of bacteria in the small intestine can lead to malabsorption and chronic diarrhea.
  • Celiac Disease: An autoimmune reaction to gluten can cause damage to the small intestine, leading to malabsorption and chronic diarrhea.

• Do Not Miss Diagnoses

  • Colon Cancer: Although less common, colon cancer can present with chronic diarrhea, especially in older adults. It is crucial to rule out this diagnosis due to its severe implications.
  • Thyrotoxicosis: Hyperthyroidism can cause an increase in bowel movements, leading to chronic diarrhea.
  • Giardiasis: Infection with Giardia lamblia can cause chronic diarrhea, especially in individuals who have traveled to areas where the parasite is common or have been exposed to contaminated water.
  • Whipple's Disease: A rare bacterial infection that can cause malabsorption, weight loss, and chronic diarrhea.

• Rare Diagnoses

  • Short Bowel Syndrome: A condition that results from a significant loss of intestinal tissue, leading to malabsorption and chronic diarrhea.
  • VIPoma: A rare tumor that secretes vasoactive intestinal peptide (VIP), causing severe, chronic diarrhea.
  • Carcinoid Syndrome: A condition caused by a neuroendocrine tumor that can produce substances leading to chronic diarrhea, among other symptoms.
  • Microscopic Colitis: A condition characterized by inflammation of the colon that can cause chronic, watery diarrhea.

Each of these diagnoses has a different set of implications for patient management and treatment, emphasizing the importance of a thorough diagnostic evaluation for chronic diarrhea.