Collagenous colitis is an inflammatory bowel condition affecting the large intestine. It is categorized under microscopic colitis, a group of conditions characterized by inflammation only visible through a microscope. This condition leads to chronic digestive issues that can significantly impact daily life.
Understanding Collagenous Colitis
Its defining feature, a thickened layer of collagen beneath the colon’s lining, is only visible under a microscope, as inflammation is not apparent during a standard colonoscopy. This abnormal collagen accumulation, often exceeding 10 micrometers in thickness, is accompanied by an increase in inflammatory cells within the colon’s wall.
The inflammation associated with collagenous colitis can interfere with the colon’s ability to reabsorb water and electrolytes, which are crucial for proper bodily function. This disruption primarily manifests as chronic, watery, non-bloody diarrhea, which can occur multiple times a day and even at night. Individuals may also experience associated symptoms such as abdominal pain, cramping, bloating, and fatigue. Unlike some other inflammatory bowel diseases, collagenous colitis does not carry an increased risk of colorectal cancer.
How Common is Collagenous Colitis?
Collagenous colitis is not considered a common disease, though its reported incidence has been increasing over recent decades. Incidence rates, which reflect the number of new cases per year, vary across different studies and geographical regions. Estimates for collagenous colitis typically range from 2 to 12 cases per 100,000 people annually. For instance, a Danish study reported an average annual incidence of 12.2 cases per 100,000 person-years between 2001 and 2016, with a peak of 19.6 cases per 100,000 in 2011.
Prevalence, which refers to the total number of people living with the condition at a given time, can be higher. Some reports indicate prevalence rates around 40 cases per 100,000 persons, while others suggest it could be as high as nearly 200 cases per 100,000 inhabitants in certain populations. The condition primarily affects older adults, with the average age at diagnosis often falling in the 60s or 70s. Women are more frequently affected than men.
Identifying and Managing Collagenous Colitis
Diagnosing collagenous colitis requires a specialized approach, as the colon’s appearance typically looks normal during a routine colonoscopy. For a definitive diagnosis, a gastroenterologist performs a colonoscopy and takes multiple small tissue samples, or biopsies, from different sections of the colon. These samples are then sent to a pathologist for microscopic examination.
The pathologist looks for specific changes, including the characteristic thickened subepithelial collagen band, along with an increase in inflammatory cells within the colon lining. This microscopic analysis is essential, as symptoms can overlap with other digestive disorders like irritable bowel syndrome, and other causes of chronic diarrhea must be ruled out.
Management focuses on controlling symptoms, as there is currently no cure. Treatment often begins with medication, with oral budesonide being a commonly recommended first-line therapy due to its anti-inflammatory properties and localized action within the gut. Other medications, such as anti-diarrheal agents like loperamide, may be used to manage symptoms, sometimes in combination with other therapies. In some cases, bismuth subsalicylate or bile acid binders like cholestyramine can also be considered.
Dietary adjustments can also play a supportive role in symptom management, although there is no universal diet for collagenous colitis. Individuals may find relief by avoiding potential trigger foods, which can include caffeine, alcohol, artificial sweeteners, and sometimes dairy or gluten if intolerances are present. During flare-ups, a temporary low-fat and low-fiber diet might help alleviate symptoms, along with ensuring adequate hydration to counteract fluid loss from diarrhea. It is also advisable to review and potentially discontinue any medications that may contribute to collagenous colitis, such as certain nonsteroidal anti-inflammatory drugs (NSAIDs) or proton pump inhibitors (PPIs). For individuals whose symptoms do not respond to initial treatments, stronger medications may be explored, and in rare, severe cases, surgical intervention might be considered.