Microscopic colitis is an inflammation of the colon that a health care provider can see only with a microscope. Inflammation is the body’s normal response to injury, irritation, or infection of tissues. Microscopic colitis is a type of inflammatory bowel disease—the general name for diseases that cause irritation and inflammation in the intestines.
The two types of microscopic colitis are collagenous colitis and lymphocytic colitis. Health care providers often use the term microscopic colitis to describe both types because their symptoms and treatments are the same.
Some scientists believe that collagenous colitis and lymphocytic colitis may be different phases of the same condition rather than separate conditions.
In both types of microscopic colitis, an increase in the number of lymphocytes, a type of white blood cell, can be seen in the epithelium—the layer of cells that lines the colon. An increase in the number of white blood cells is a sign of inflammation. The two types of colitis affect the colon tissue in slightly different ways:
- Lymphocytic colitis. The number of lymphocytes is higher, and the tissues and lining of the colon are of normal thickness.
- Collagenous colitis. The layer of collagen, a threadlike protein, underneath the epithelium builds up and becomes thicker than normal.
When looking through a microscope, the health care provider may find variations in lymphocyte numbers and collagen thickness in different parts of the colon.
These variations may indicate an overlap of the two types of microscopic colitis.
Symptoms of collagenous colitis and lymphocytic colitis
Symptoms and signs may include:
- watery diarrhoea that does not contain blood or pus
- the diarrhoea may be chronic, or may come and go
- bowel incontinence
- abdominal cramps
- abdominal bloating and discomfort
Complications of collagenous colitis and lymphocytic colitis
- Without treatment, complications may include:
- malabsorption of food nutrients
- weight loss
What causes microscopic colitis?
The exact cause of microscopic colitis is unknown. Several factors may play a role in causing microscopic colitis.
However, most scientists believe that microscopic colitis results from an abnormal immune-system response to bacteria that normally live in the colon. Scientists have proposed other causes, including
- autoimmune diseases
- genetic factors
- bile acid malabsorption
- Autoimmune Diseases
Sometimes people with microscopic colitis also have autoimmune diseases—disorders in which the body’s immune system attacks the body’s own cells and organs. Autoimmune diseases associated with microscopic colitis include:
- celiac disease—a condition in which people cannot tolerate gluten because it damages the lining of the small intestine and prevents absorption of nutrients. Gluten is a protein found in wheat, rye, and barley.
thyroid diseases such as
- Hashimoto’s disease—a form of chronic, or long lasting, inflammation of the thyroid.
- Graves’ disease—a disease that causes hyperthyroidism. Hyperthyroidism is a disorder that occurs when the thyroid gland makes more thyroid hormone than the body needs.
- rheumatoid arthritis—a disease that causes pain, swelling, stiffness, and loss of function in the joints when the immune system attacks the membrane lining the joints.
- psoriasis—a skin disease that causes thick, red skin with flaky, silver-white patches called scales.
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Researchers have not found that medications cause microscopic colitis. However, they have found links between microscopic colitis and certain medications, most commonly
- nonsteroidal anti-inflammatory drugs such as aspirin, ibuprofen, and naproxen
- lansoprazole (Prevacid)
- acarbose (Prandase, Precose)
- ranitidine (Tritec, Zantac)
- sertraline (Zoloft)
- ticlopidine (Ticlid)
Other medications linked to microscopic colitis include:
- clozapine (Clozaril, FazaClo)
- dexlansoprazole (Kapidex, Dexilant)
- entacapone (Comtan)
- esomeprazole (Nexium)
- flutamide (Eulexin)
- lisinopril (Prinivil, Zestril)
- omeprazole (Prilosec)
- pantoprazole (Protonix)
- paroxetine (Paxil, Pexeva)
- rabeprazole (AcipHex)
- simvastatin (Zocor)
- vinorelbine (Navelbine)
- Bacteria. Some people get microscopic colitis after an infection with certain harmful bacteria. Harmful bacteria may produce toxins that irritate the lining of the colon.
- Viruses. Some scientists believe that viral infections that cause inflammation in the GI tract may play a role in causing microscopic colitis.
Some scientists believe that genetic factors may play a role in microscopic colitis. Although researchers have not yet found a gene unique to microscopic colitis, scientists have linked dozens of genes to other types of inflammatory bowel disease, including
- Crohn’s disease—a disorder that causes inflammation and irritation of any part of the GI tract
- ulcerative colitis—a chronic disease that causes inflammation and ulcers in the inner lining of the large intestine
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- Crohn’s Disease
- Ulcerative Colitis
- Bile Acid Malabsorption
Some scientists believe that bile acid malabsorption plays a role in microscopic colitis. Bile acid malabsorption is the intestines’ inability to completely reabsorb bile acids––acids made by the liver that work with bile to break down fats.
Bile is a fluid made by the liver that carries toxins and waste products out of the body and helps the body digest fats. Bile acids that reach the colon can lead to diarrhea.
Diagnosis of collagenous colitis and lymphocytic colitis
Most people are diagnosed between the ages of 60 and 80. The symptoms of collagenous colitis and lymphocytic colitis are similar to other gastrointestinal illnesses such as irritable bowel syndrome, Crohn’s disease and ulcerative colitis.
Diagnosis may include:
- medical history
- physical examination
- tests (such as a stool culture) to rule out other gastrointestinal diseases
- colonoscopy, the use of a slender viewing tube inserted into the colon via the anus to view the entire length of the colon. The lining of the colon should appear normal.
- flexible sigmoidoscopy, the use of a viewing tube inserted through the anus to view the rectum. The lining of the rectum should appear normal
- biopsy, the removal of a small tag of tissue for examination in a laboratory, is essential for diagnosis. Changes, including an abnormally thick collagen layer or a build-up of lymphocytes, are visible under the microscope.
- Multiple biopsies must be taken.
Treatment of collagenous colitis and lymphocytic colitis
There is no cure, but treatment can manage the symptoms. Treatment options depend on the severity of the symptoms, but may include:
- Watchful waiting – some patients with mild symptoms improve without any treatment, for reasons unknown.
- Dietary changes – some foods and drinks aggravate diarrhoea. Your doctor may advise you to cut down on fatty or spicy foods, milk products, alcohol, sugary drinks and caffeine. Avoid gas-promoting products such as beans, cabbage and fizzy drinks. Opt for soft and easy to digest foods such as bananas and rice. Eat frequent small meals throughout the day, rather than three large meals.
- Switching medicines – some evidence suggests that non-steroidal anti-inflammatory drugs, including aspirin and ibuprofen, can worsen symptoms. Your doctor may recommend that you try different medicines, if possible, to see if symptoms improve.
- Anti-diarrhoea medication – this slows the passage of faeces through the colon.
- Other medications – if the above measures don’t seem to help, your doctor may suggest stronger medications such as corticosteroids to help ease the symptoms. Non-absorbable steroids (budesonide) often help.
- Medications containing 5-aminosalicylic acid (5ASAs) may also help.
- Surgery would rarely be necessary.
How can microscopic colitis be prevented?
Researchers do not know how to prevent microscopic colitis. However, researchers do believe that people who follow the recommendations of their health care provider may be able to prevent relapses of microscopic colitis.
Does microscopic colitis increase the risk of colon cancer?
No. Unlike the other inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, microscopic colitis does not increase a person’s risk of getting colon cancer.