Microscopic Colitis
Microscopic colitis (MC) is a form of inflammatory bowel disease characterized by sudden, chronic watery diarrhea without blood. On average, diarrhea occurs six to nine times a day, but it can be more than ten. For many individuals, about one-third of these episodes happen at night, severely disrupting sleep and contributing to fatigue.
Other symptoms include fecal incontinence, abdominal discomfort or pain, weight loss, nausea, and vomiting. For some individuals, MC presents mainly as chronic constipation or they might experience constipation following episodes of diarrhea.
There are two subtypes of microscopic colitis.
- Collagenous colitis is defined by a thickened layer of sub-epithelial collagen.
- Lymphocytic colitis involves an increased number of immune system cells within the epithelial layer of the digestive tract.
The incidence of MC is approximately 11 for every 100,000 individuals annually. However, this is likely a significant underestimation since the disease is not widely known among the public and healthcare professionals, leading to frequent misdiagnoses as other digestive disorders.1
MC affects more women than men, with onset commonly occurring among those older than 62 years of age. However, it can manifest at any age, with some cases occurring in people under 45, and in rare instances, among children.
Risk Factors
Studies have identified associations between the following risk factors and the development of microscopic colitis:1
- smoking (past and ongoing)
- a prior Clostridioides difficile infection (C. diff infection)
- past or current use of certain medications (i.e., proton pump inhibitors, non-steroidal anti-inflammatory drugs, selective serotonin reuptake inhibitors, immune checkpoint inhibitors)
- having the HLA-DQ2 haplotype gene
Microscopic colitis is also associated with diagnosis of other autoimmune diseases (i.e., celiac disease, Hashimoto’s thyroiditis, rheumatoid arthritis, Sjögren’s syndrome, psoriasis, type 1 diabetes) and bile acid absorption disorders.
Diagnosis
Diagnosis begins with a thorough review of your medical history and when and how symptoms began, particularly the nature of diarrhea and its duration. If diarrhea persists for more than four weeks, clinical guidelines recommend performing an ileocolonoscopy with biopsies taken from the left and right sides of the colon for examination.2
It is crucial for physicians to biopsy several locations for an accurate diagnosis since errors may occur from changes in the clinical presentation of MC over time. Unfortunately, researchers have yet to identify reliable biomarkers that can support diagnosis and monitoring of the disease.
Management
There are several ways to manage and treat microscopic colitis. This includes lifestyle changes, such as quitting smoking and reducing alcohol consumption. While research is limited on the role of diet, some suggest that a high intake of dietary calcium might have protective effects against the development of MC.1
The goal of microscopic colitis treatment is to achieve remission. This means having fewer than three bowel movements per day, and ideally none presenting as watery stool. Physicians will also advise discontinuing medications that may cause diarrhea, if applicable.
To induce and maintain remission, budesonide is the gold standard of treatment for all subtypes of MC.2 Budesonide is available as oral tablets (Cortiment®, Entocort®), enemas (Entocort® Enema), and rectal foams (Uceris™). While their use is off-label because Health Canada has not approved microscopic colitis as an indication for these medications, several studies have found that budesonide is safe for long-term use and has limited side effects. You can learn more about these medications by using our interactive IBD Medication Guide.
For individuals with bile acid-related diarrhea, your healthcare provider might prescribe bile acid sequestrants, such as cholestyramine, colesevelam hydrochloride, and colestipol hydrochloride.
If budesonide is ineffective, physicians may recommend thiopurines or certain biologics, such as infliximab (originator: Remicade®; biosimilars: Avsola®, Inflectra®, Ixifi®, Omvyence™, Remsima™SC, Renflexis®), adalimumab (originator: Humira®; biosimilars: Abrilada®, Amgevita®, Hadlima®, Hadlima® PushTouch®, Hulio®, Hyrimoz®, Idacio®, Simlandi™, Yuflyma™), or vedolizumab (Entyvio®). Healthcare providers may also consider a combination of these medications.
Surgery is rare and is a last resort when medications do not work to achieve remission. This includes conducting a permanent ileostomy, which involves re-directing the small intestine to the surface of the skin, called a stoma, to bypass the colon. Due to its rarity, there is limited data on best practices for its implementation in the care journey.
MC and Other Digestive Conditions
Microscopic colitis shares symptoms with several other gastrointestinal conditions, such as irritable bowel syndrome (IBS), celiac disease, and other inflammatory bowel diseases (IBDs). However, distinguishing it from these conditions can be difficult due to limited awareness among healthcare professionals and the public, as well as challenges in accessing screening and biopsy techniques. This often results in misdiagnoses and delays in receiving appropriate care.
Irritable Bowel Syndrome
Some of the symptoms of microscopic colitis are similar to IBS, which is a chronic functional disorder that presents with abdominal pain, bloating, and altered bowel behaviours, such as constipation and/or diarrhea, or alternating between the two. Research shows that approximately 39% of individuals with MC have reported symptoms of IBS.3 However, it should be noted that IBS generally does not disrupt your sleep, while diarrhea caused by MC often occurs at night.
Celiac Disease
Both microscopic colitis and celiac disease share the risk factor of the HLA-DQ2 haplotype gene. The United European Gastroenterology and European Microscopic Colitis Group recommends that individuals with celiac disease who experience chronic diarrhea should undergo a colonic biopsy to screen for microscopic colitis.2
Inflammatory Bowel Disease
Unlike other inflammatory bowel diseases, such as Crohn’s disease or ulcerative colitis, there are no extra-intestinal manifestations with microscopic colitis. MC also does not increase your risk of colorectal cancer or mortality. However, its symptoms can be debilitating and have a significant impact on quality of life.
Outlook
There is an urgent need for more research to improve our understanding of microscopic colitis to pave the way for better screening approaches and effective therapies. Increased awareness among healthcare professionals and the public are critical to recognize the signs and symptoms of microscopic colitis, enabling timely diagnosis and care.
