What is microscopic colitis?
Microscopic colitis is an inflammatory bowel disease in which the colon (the large intestine) becomes inflamed (swollen, irritated). There are two types of microscopic colitis, lymphocytic colitis and collagenous colitis:
- Patients who have lymphocytic colitis have an increase in lymphocytes (white blood cells) in the epithelium (the lining of the colon).
- In patients who have collagenous colitis, the layer of collagen (fibrous connective tissue) under the epithelium becomes thicker.
Women, people over the age of 50 and people who have an autoimmune disease (the immune system attacks the body) are more likely to have microscopic colitis.
Symptoms and Causes
What causes microscopic colitis?
Microscopic colitis may have several different causes, including the following:
- Certain autoimmune diseases, including celiac disease, thyroid diseases, rheumatoid arthritis and psoriasis
- Medications, including nonsteroidal anti-inflammatory drugs such as aspirin, ibuprofen and naproxen; antacid and heartburn drugs; antidepressants; and certain drugs for treatment of cancer or heart disease
- Infections (caused by bacteria or viruses)
- Genetics (heredity)
What are the symptoms of microscopic colitis?
The main symptom of microscopic colitis is non-bloody diarrhea, which the patient may have for some time. Other symptoms include:
- Always feeling like you need to have a bowel movement
- Weight loss
- Pain and cramping in the abdomen
- Fecal incontinence (leaking stool, caused by inability to control bowel movements)
- Dehydration (extreme thirst)
- Bile acid malabsorption. Bile is made and released by the liver and then sent through tube-like structures called bile ducts to the small intestine, where it helps the body break down and absorb food. In bile acid malabsorption, something, such as a stone, is blocking the flow of bile from the liver and gallbladder to the intestine.
Diagnosis and Tests
How is microscopic colitis diagnosed?
Microscopic colitis is usually diagnosed by a gastroenterologist (a specialist in diseases of the digestive system). The gastroenterologist will perform a physical examination and will ask you about your symptoms and any medications you are taking.
The doctor may also order certain tests, including:
- Blood tests
- Lab tests
- Stool tests
- Imaging tests, such as computed tomography (CT), magnetic resonance imaging (MRI) and upper GI (the patient has an X-ray after drinking a barium solution, which causes the organs to show up more sharply) of the colon
The test that is most often used to make a definitive diagnosis of microscopic colitis is a colonoscopy with a biopsy. During a colonoscopy, the doctor uses a colonoscope (a long, flexible instrument about 1/2 inch in diameter) to view the lining of the colon. The colonoscope is inserted into the rectum and advanced through the large intestine. If necessary, small amounts of tissue can be removed for analysis (a biopsy) and polyps can be identified and entirely removed.
Management and Treatment
How is microscopic colitis treated?
Microscopic colitis can get better on its own, but most patients have recurrent symptoms.
The main treatment for microscopic colitis is medication. In many cases, the doctor will start treatment with an antidiarrheal medication such as Pepto-Bismol® or Imodium® .
Other medications the doctor can prescribe include:
- Corticosteroids, man-made drugs that closely resemble cortisol (a hormone that your adrenal glands produce). Steroids work by decreasing inflammation and reducing the activity of the immune system. The two steroids most often prescribed for microscopic colitis are budesonide (Entocort®) and prednisone. Budesonide is believed to be the safest and most effective medication for treating microscopic colitis.
- Cholestyramine resin (Locholest®, Questran®), which blocks bile acids
- Mesalamine (Apriso®, Asacol®) and sulfasalazine (Azulfidine®) to reduce swelling
- Medications that work on the immune system, such as mercaptopurine (Purinethol®), azathioprine (Azasan®, Imuran®), and methotrexate (Rheumatrex®, Trexall®)
- Tumor Necrosis Factor (TNF) inhibitors such as infliximab (Remicade®) and adalimumab (Humira®)
The doctor may also recommend that you avoid certain foods, such as caffeine or artificial sugars.
As a last resort when medications are not working, the doctor may recommend surgery to remove part or all of the colon.
Can microscopic colitis be prevented?
There is no way to prevent microscopic colitis, but treating it properly may help prevent the disease from returning. Having microscopic colitis does not increase the chances of getting colon cancer.