About Microscopic colitis
Microscopic colitis is a disorder characterized by intermittent to chronic watery non-bloody diarrhea with a normal-appearing colon on colonoscopy or CT scan. However, upon biopsy of the colon, microscopic evidence of inflammation can be observed; hence the term microscopic colitis. Pathologically, this inflammation is characterized by inflammatory immune cells called lymphocytes or the deposition of a type of material along the lining of the colon called collagen, giving rising the two distinct subtypes of microscopic colitis called lymphocytic colitis and collagenous colitis.
What causes microscopic colitis?
The incidence of microscopic colitis is rising. It has been estimated that 10–20% of all cases with chronic non-bloody diarrhea are due to microscopic colitis. The disorder is likely caused by multiple factors including but not limited to genetics and possible drug exposure.
- A genetic basis for microscopic colitis is suspected, but further studies need to be performed to establish this hypothesis and, if found to be true, to identify the genes responsible for increased risk for developing the disease. A high proportion of microscopic colitis patients also have associated autoimmune disorders with a genetic basis including celiac disease, arthritis, thyroiditis and type I diabetes mellitus. Thus, microscopic colitis may be considered potentially an autoimmune disease.
- Although not definitive, a variety of drugs have been considered possible triggers for microscopic colitis such as non-steroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen and naproxen) and proton-pump inhibitors (PPIs, such as Prilosec, Nexium and Protonix), but are unlikely to be the sole cause given their widespread use in the general population.
How is microscopic colitis diagnosed?
Because the gross appearance of the mucosa is most often normal, the diagnosis of microscopic colitis depends on the histological examination of colonic biopsy tissue by a pathologist. If a patient is suffering from unexplained diarrhea, a doctor has to be aware of this condition and take biopsies during colonoscopy. Clinical symptoms include:
- Watery non-bloody diarrhea
- Mild diffuse abdominal discomfort
- Generally no significant weight loss
- Negative work-ups for other causes of diarrhea such as inflammatory bowel disease (such as Crohn's disease and ulcerative colitis) as well as infections
How is microscopic colitis treated?
Microscopic colitis is often a challenging disease requiring individualized patient treatment programs with a strong long-term doctor-patient relationship, as patients often can have relapses of their symptoms and disease.
- Removal of potential medication triggersInitially, our physicians will carefully review a patient's medication lists and medications suspected of contributing or exacerbating microscopic colitis such as aspirin, ibuprofen and naproxen will be discontinued if medically possible.
There are number of medical treatments that can be offered to patients with microscopic colitis depending on severity and duration of symptoms. Therapies range from simple antidiarrheal medications to non-systemically absorbed steroids or anti-inflammatory medications, to strong systemic immunosuppressive medications for patients with refractory or difficult to control symptoms.