Fecal calprotectin is a protein found in stool that serves as a marker for inflammation within the intestines. This protein is released by neutrophils, which are a type of white blood cell, when they migrate to areas of inflammation in the gastrointestinal tract. Elevated levels of fecal calprotectin can indicate the presence of various gastrointestinal issues, signaling a need for further medical evaluation.
Understanding Fecal Calprotectin and Its Measurement
Calprotectin is a protein primarily found in neutrophils. When inflammation occurs in the gut, these neutrophils move to the affected area and release calprotectin, which then passes into the stool. The amount of calprotectin detected in a stool sample generally correlates with the severity of intestinal inflammation.
Measuring fecal calprotectin involves a non-invasive stool sample test. This test helps detect intestinal inflammation. After collection, the sample is sent to a laboratory for analysis.
An “elevated” result means the calprotectin level in the stool is above a certain threshold. Specific normal ranges can vary between laboratories, but an elevated result indicates inflammation.
Conditions Associated with Elevated Fecal Calprotectin
Elevated fecal calprotectin levels can be linked to several conditions that cause inflammation in the gastrointestinal tract. One of the most common and significant associations is with Inflammatory Bowel Disease (IBD), which includes Crohn’s disease and ulcerative colitis. These are chronic conditions characterized by ongoing inflammation of the intestinal wall, leading to symptoms like diarrhea, abdominal pain, and weight loss.
Gastrointestinal infections, caused by bacteria, viruses, or parasites, can also lead to temporary increases in fecal calprotectin. These infections trigger an inflammatory response as the body attempts to fight off the pathogens. Once the infection resolves, calprotectin levels typically return to normal.
Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) can irritate the lining of the gut, causing a condition known as NSAID-induced enteropathy. This irritation can result in intestinal inflammation and, consequently, elevated calprotectin levels. Similarly, active celiac disease, an autoimmune condition triggered by gluten, can cause inflammation in the small intestine, leading to higher calprotectin readings.
Some cases of colorectal cancer may also be associated with elevated fecal calprotectin, often due to inflammation or bleeding in the bowel. Other less common causes of elevated calprotectin include diverticulitis, which is the inflammation of pouches in the digestive tract, and microscopic colitis, an inflammatory condition diagnosed through microscopic examination of colon tissue. It is important to remember that calprotectin is a marker of inflammation in general, not a specific disease.
Interpreting Elevated Results and Subsequent Steps
An elevated fecal calprotectin level indicates intestinal inflammation but does not provide a specific diagnosis on its own. It serves as an indicator that further investigation is necessary to pinpoint the underlying cause of the inflammation.
One of the primary uses of fecal calprotectin is to help differentiate between inflammatory bowel conditions, such as IBD, and non-inflammatory conditions, like Irritable Bowel Syndrome (IBS). While both can present with similar symptoms like abdominal pain and diarrhea, IBD involves actual inflammation and damage to the intestinal lining, whereas IBS is a functional disorder without structural changes. Fecal calprotectin is typically elevated in IBD but not in IBS, providing a valuable distinction that guides treatment approaches.
For individuals already diagnosed with IBD, fecal calprotectin testing plays a role in monitoring disease activity and assessing treatment effectiveness. It can also help predict potential relapses, even when a patient is in clinical remission and experiencing no symptoms. A significant increase in calprotectin levels could signal an impending flare-up, allowing for proactive adjustments to treatment.
Following an elevated fecal calprotectin result, a healthcare provider, often a gastroenterologist, will likely recommend additional diagnostic tests. These may include a colonoscopy or endoscopy to visually examine the intestinal lining and collect tissue samples for biopsy, imaging studies, specific blood tests, or stool cultures to rule out infections. The interpretation of these results is always done in conjunction with a patient’s symptoms and medical history.