From the Guidelines
Definition of Microscopic Colitis
Microscopic colitis is a chronic inflammatory bowel disease characterized by microscopic inflammation of the colonic mucosa, typically presenting with chronic watery diarrhea 1.
Key Characteristics
The condition is diagnosed by colonic biopsy and is not associated with increased mortality, although symptoms can lead to impaired quality of life 1. It comprises two subtypes: lymphocytic colitis and collagenous colitis, with a female predominance in the latter 1.
Diagnosis and Treatment
Diagnosis involves colonoscopy with biopsies of multiple segments of the colon, and treatment focuses on relieving symptoms and improving quality of life while minimizing drug-related adverse effects 1. Loperamide 2-4 mg orally three to four times daily can be used for symptom control, and budesonide 9 mg orally once daily for 6-8 weeks can induce clinical remission 1. For patients who do not respond to budesonide, alternative therapies such as mesalamine 1.5-3 grams orally twice daily or azathioprine 1-2 mg/kg orally once daily may be considered, with treatment durations tailored to individual patient responses 1.
Important Considerations
Patients with refractory symptoms should avoid potential medication triggers such as nonsteroidal anti-inflammatory drugs, proton pump inhibitors, and selective serotonin reuptake inhibitors 1. Coexisting causes of chronic diarrhea, such as celiac disease, should also be considered, and the persistence of residual bowel symptoms may reflect coexisting or postinflammatory functional bowel disorders 1.
From the Research
Definition and Characteristics of Microscopic Colitis
- Microscopic colitis (MC) is an inflammatory disease of the colon and a common cause of chronic watery diarrhea, predominantly in older patients 2.
- It encompasses 2 different subtypes, lymphocytic colitis and collagenous colitis, with the colon typically appearing normal endoscopically in MC, and the diagnosis requires histologic evaluation 2, 3.
- MC is characterized by normal or almost normal endoscopic appearance of the colon, chronic watery, nonbloody diarrhoea and distinct histological abnormalities 3.
Clinical Presentation and Risk Factors
- The clinical presentation of MC is nonspecific and includes watery nonbloody diarrhea, nocturnal stools, fecal urgency, abdominal pain, arthralgias, and weight loss 2.
- Risk factors for MC include increasing age, female sex, presence of other autoimmune diseases, and possibly use of certain medications, including proton pump inhibitors, nonsteroidal anti-inflammatory drugs, selective serotonin reuptake inhibitors, and statins 2.
Diagnosis and Treatment
- Diagnosis of MC requires colonoscopy using random biopsies from various parts of the colon, as reliable biomarkers are unavailable 4.
- A 6-8-week oral budesonide treatment course (9 mg/day) is considered the first-line therapy, but patients often experience relapse when discontinued, or might become intolerant, dependent, or even fail to respond 4.
- Other therapeutic options, such as bismuth subsalicylate, biologics, loperamide, bile acid sequestrants, and thiopurines, may be prescribed for patients who do not respond to budesonide or experience relapse 5, 6, 4.
- Budesonide has been shown to be associated with increased clinical remission rates compared with mesalamine, especially after 8 weeks of follow-up, and has a lower incidence of adverse events 5.