What are the other Names for this Condition? (Also known as/Synonyms)

• Collagenous Colitis
• Lymphocytic Colitis

What is Microscopic Colitis? (Definition/Background Information)

• Microscopic Colitis is an inflammation of the large bowel that is more prevalent in individuals over the age of 50 years. It is a type of inflammatory bowel disease (IBD) that can be diagnosed by taking a tissue sample from the colon (during a colonoscopy) and examining it under a microscope
• Smoking, having an autoimmune disorder, or being on certain medications are known to be linked to Microscopic Colitis. Several factors such as bile acid malabsorption, certain autoimmune disorders, medications, and bacterial or viral infections are known to contribute towards Microscopic Colitis development. Research is currently ongoing to understand the genetic basis for the disease
• Chronic watery diarrhea with intermittent symptom-free periods is considered a classic symptom of Microscopic Colitis. Additionally, the individual may have abdominal cramps. In case of delayed or lack of treatment, some potential complications of Microscopic Colitis may include dehydration, malabsorption of nutrients, which can result in malnutrition and consequential weight loss
• Some options for treating Microscopic Colitis include the administration of anti-diarrheal, antibiotic, anti-inflammatory drugs, and the discontinuation of medication that is suspected of causing symptoms
• Although, there is no cure for Microscopic Colitis, the condition is manageable with certain lifestyle changes and medication. In many patients, the condition is reported to resolve on its own during the course of time

Microscopic Colitis is classified into 2 subtypes, depending on the type of cells or molecules that are augmented in the condition. These include:

• Lymphocytic Colitis: In this type, there is an accumulation of lymphocytes (a type of white blood cells) within the lining of the colon
• Collagenous Colitis: In this type, there is an additional layer of a protein called collagen (scar tissue) just below the lining of the colon

Some experts believe that Lymphocytic Colitis and Collagenous Colitis represent different stages of the same disease.

Who gets Microscopic Colitis? (Age and Sex Distribution)

• Middle-aged and older individuals above 50 years are more susceptible to Microscopic Colitis
• The condition affects both male and female genders, but is more common among women than men
• All races and ethnic groups are at risk and no specific preference is noted

What are the Risk Factors for Microscopic Colitis? (Predisposing Factors)

The following are some of the risk factors for developing Microscopic Colitis:

• Feminine gender, especially being a middle-aged woman
• Older adults, over 50 years of age
• A history of smoking
• Autoimmune disorders that include celiac disease, rheumatoid arthritis, psoriasis (skin condition), and Hashimoto’s disease and Graves’ disease (both affecting the thyroid gland)
• The use certain medications such as:
  • Clozapine (Clozaril)
  • Entacapone (Comtan)
  • Esomeprazole (Nexium)
  • Flutamide
  • Lansoprazole (Prevacid)
  • Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen (Advil, Motrin, and others)
  • Omeprazole (Prilosec)
  • Ranitidine (Zantac)
  • Sertraline (Zoloft)
  • Simvastatin (Zocor)
  • Ticlopidine (Ticlid)

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Microscopic Colitis? (Etiology)

Although the exact cause of Microscopic Colitis is not known at the present time, there exist several factors which might contribute to the development of the disease. These include:

• Bacterial infections that produce toxins that irritate the lining of the colon
• Certain viruses that trigger inflammation
• Immune system related conditions, such as autoimmune disorders, which occur when the body immune system attacks one’s own healthy tissues. Individuals with Collagenous Colitis or Lymphocytic Colitis sometimes also have an autoimmune disorder, such as celiac disease (a condition when the small gut causes malabsorption), rheumatoid arthritis (disorder affecting the joints), or scleroderma (disorder affecting the skin)
• Medications: Several medications are reported to increase the risk for Microscopic Colitis
• Genetic factors: Although still under active research, some scientists believe that there might be certain genes associated with Microscopic Colitis, as reported for other types of inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis
• Bile acid malabsorption: It is well known that the presence of bile acid in the intestines can cause diarrhea. With this basis, some scientists believe that a potential cause of Microscopic Colitis could be the incomplete absorption of bile acids by the intestines, leading to the associated symptoms

What are the Signs and Symptoms of Microscopic Colitis?

The following are some typical symptoms associated with Microscopic Colitis:

• Chronic watery diarrhea for weeks to months
• Symptoms are intermittent in nature with periods of no symptoms (the symptoms ‘come and go’)
• Mild abdominal cramps
• Bleeding from the rectum, in some cases

How is Microscopic Colitis Diagnosed?

A healthcare provider might employ one or more of the following methods to arrive at a diagnosis of Microscopic Colitis:

• Complete physical examination with an assessment of the symptoms
• A review of personal medical history (including history of autoimmune diseases, medications taken, diet, etc.)
• Colonoscopy: Extracting a tissue sample of the colon while examining the organ (using a tube with a light source and camera, which helps visualise the inner lining of the large bowel/colon) and studying it under a microscope. This is an important diagnostic tool; however, the findings are usually normal. Hence, random colon biopsies are taken and sent to the pathologist to ensure a definitive diagnosis of the condition
• Blood tests
• Stool test
• Upper GI series: X-ray examination of the upper gastrointestinal tract
• Computed tomography or magnetic resonance imaging (MRI) scans of the colon

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Microscopic Colitis?

• Owing to watery diarrhea, there is a possibility of dehydration in Microscopic Colitis
• Other complications include malabsorption of nutrients and consequent malnutrition, leading to weight loss

How is Microscopic Colitis Treated?

Treatment options for Microscopic Colitis depend on several factors that include:

• Whether there exists an active infection,
• If the patient suffers from an autoimmune disorder
• Or, if he/she is on certain medications

Some known treatment methods for Microscopic Colitis include:

• Anti-diarrheal medications
• Anti-inflammatory medications such as 5-ASA (mesalamine)
• Antibiotics, for bacterial infections
• Advice to avoid certain medications and food items, such as
  • Non-steroidal anti-inflammatory drugs or NSAIDs
  • Lactose, to eliminate the possibility that intolerance to lactose in milk is aggravating the diarrhea
• Administration of corticosteroids
• Bismuth subsalicylate (Pepto-Bismol) to treat stomach discomfort
• Cholestyramine resin to block bile acids
• Suitably modifying one’s diet or following a dietician-approved diet may be beneficial to some
• In very rare cases, the healthcare provider may recommend a surgery to treat the condition

Some controlled clinical trials have shown that budesonide (a poorly absorbed steroid) is effective in controlling diarrhea in more than 75% of the patients with Collagenous Colitis. However, the diarrhea tends to recur soon after stopping the drug.

Though data supporting their use is lacking, some healthcare providers may use medications that potently suppress the immune system, such as azathioprine and 6-mercaptopurine, in patients with severe Microscopic Colitis, which is unresponsive to other treatment measures.

How can Microscopic Colitis be Prevented?

Currently, it is not possible to prevent the development of Microscopic Colitis.

• However, early and proper treatment may control the symptoms and prevent recurrences
• Also, if the condition is associated with the use of certain drugs and medications, then discontinuation of the same may help avoid Microscopic Colitis

What is the Prognosis of Microscopic Colitis? (Outcomes/Resolutions)

• There is no specific cure for Microscopic Colitis. However, it is possible to manage the symptoms with prompt and appropriate treatment
• In two-thirds of the individuals with Microscopic Colitis, the diarrhea is reported to resolve spontaneously after several years
• Some patients, however, might suffer from intermittent diarrhea indefinitely

Additional and Relevant Useful Information for Microscopic Colitis:

There are many different types of colitis (inflammation of the colon/ large bowel) based on the causative factors and these include:

• Infectious colitis
• Ischemic colitis
• Radiation colitis
• Ulcerative colitis