What Is Microscopic Colitis?

Microscopic colitis is a type of inflammation in the large intestine (colon) that causes chronic, watery diarrhea. It is called “microscopic” because the lining of the colon looks normal during a colonoscopy — the inflammation can only be seen under a microscope when a small tissue sample (biopsy) is examined.

There are two main types of microscopic colitis:

• Collagenous colitis — characterized by a thickened layer of a protein called collagen beneath the surface of the colon lining.
• Lymphocytic colitis — characterized by an increased number of white blood cells (lymphocytes) in the colon lining.

Both types cause similar symptoms and are treated the same way.

Symptoms

The hallmark symptom of microscopic colitis is chronic, watery, non-bloody diarrhea. Other common symptoms include:

• Frequent bowel movements, including at night
• Urgent need to have a bowel movement (fecal urgency)
• Fecal incontinence (accidental leakage of stool)
• Abdominal cramping or pain

Symptoms can come and go. Some people have mild, occasional episodes, while others experience more persistent and bothersome symptoms. Microscopic colitis is not life-threatening, but it can significantly affect quality of life.

Risk Factors

Several factors may increase the chance of developing microscopic colitis:

• Age: Most people are diagnosed after age 50, though it can affect all ages
• Sex: Women are about three times more likely than men to develop this condition.
• Certain medications: Some commonly used medications have been linked to microscopic colitis, including:
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen
  • Proton pump inhibitors (PPIs) such as omeprazole and pantoprazole
  • Selective serotonin reuptake inhibitors (SSRIs), a type of antidepressant
• Autoimmune conditions: People with autoimmune diseases — such as thyroid disease (Hashimoto’s thyroiditis), celiac disease, or rheumatoid arthritis — are at higher risk.
• Smoking: Tobacco use has been associated with microscopic colitis.

Diagnosis

Microscopic colitis cannot be diagnosed by symptoms, lab tests, or imaging alone. The diagnosis requires:

1. Colonoscopy: A procedure in which a flexible camera is used to examine the inside of the colon. In microscopic colitis, the colon usually looks completely normal.
2. Biopsies: During the colonoscopy, the doctor takes small tissue samples from different areas of the colon. These samples are examined under a microscope by a pathologist, who looks for the characteristic signs of inflammation that confirm the diagnosis.

Because the colon appears normal on colonoscopy, biopsies are essential — without them, the condition would be missed.

Treatment

The goal of treatment is to relieve symptoms and improve quality of life. Microscopic colitis does not increase the risk of colon cancer.

Reviewing your medication list carefully and removing predisposing medications can help, though may not be enough to control diarrhea.

The mainstay of treatment is an anti-inflammatory medication called budesonide.  Budesonide is a steroid, but typical steroid side effects such as bone and muscle loss are limited by the fact that budesonide is 90% broken down by the liver before it reaches the rest of the body.  It is generally given in limited courses to control microscopic colitis.  The diarrhea may come back after varying amounts of time and require additional courses of budesonide, or sometimes a low dose maintenance treatment.

If you have any questions, don’t hesitate to reach out to our team at Salem Gastro.