What are the causes of microscopic colitis?

From the Guidelines

The exact cause of microscopic colitis remains unknown, but several factors, including medications, autoimmune conditions, bacterial infections, genetic factors, bile acid malabsorption, and environmental factors, likely contribute to its development. According to the American Gastroenterological Association Institute guideline on the medical management of microscopic colitis 1, medications such as nonsteroidal anti-inflammatory drugs, proton pump inhibitors, and selective serotonin reuptake inhibitors can precipitate microscopic colitis, especially in those who are refractory to medical therapy.

Some key factors that may contribute to the development of microscopic colitis include:

• Medications: NSAIDs, proton pump inhibitors, selective serotonin reuptake inhibitors, and statins
• Autoimmune conditions: rheumatoid arthritis, celiac disease, and thyroid disorders
• Bacterial infections or toxins: may damage the colon lining, initiating inflammation
• Genetic factors: microscopic colitis sometimes runs in families
• Bile acid malabsorption: can irritate the colon and contribute to symptoms
• Environmental factors: smoking doubles the risk of developing the condition
• Age and sex: microscopic colitis most commonly affects people over 50, particularly women

As noted in the guideline 1, the goal of medical therapy is to relieve symptoms and improve quality of life while minimizing drug-related adverse effects. The guideline does not distinguish between subtypes of microscopic colitis, including lymphocytic colitis and collagenous colitis, as outcomes did not differ between them.

It is essential to consider coexisting causes of chronic diarrhea, such as celiac disease, and postinflammatory functional bowel disorders in patients with microscopic colitis who have ongoing symptoms despite medical therapy 1. Additionally, patients with refractory symptoms should avoid potential medication triggers.

Overall, the development of microscopic colitis is likely the result of a complex interplay between various factors, and a comprehensive approach to management is necessary to improve patient outcomes.

From the Research

Causes of Microscopic Colitis

The causes of microscopic colitis are not fully understood, but several risk factors have been identified, including:

• Increasing age 2, 3, 4
• Female sex 2, 3, 4
• Presence of other autoimmune diseases 2, 3, 4
• Use of certain medications, such as:
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) 2, 3, 5, 6
  • Proton pump inhibitors (PPIs) 2, 3, 4
  • Selective serotonin reuptake inhibitors (SSRIs) 2, 3
  • Statins 2
• Smoking 3, 4
• Alcohol consumption 4
• Genetic factors 4
• Bile acid malabsorption 4
• Obesity 4
• Appendicitis 4
• Intestinal dysbiosis 4

Medication-Associated Risk

Some studies have investigated the association between medication use and microscopic colitis, with findings including:

• An inverse association between MC and use of PPIs, H2 blockers, and oral diabetes medications 5
• A positive association between NSAID use and MC 5, 6
• No association between MC and other previously implicated medications, including SSRIs 6