Calprotectin is a protein biomarker, commonly measured in stool samples to assess inflammation within the gastrointestinal tract. This non-invasive test helps evaluate intestinal health.
What is Calprotectin and Its Purpose?
Calprotectin is a protein primarily released by neutrophils, a type of white blood cell. When inflammation occurs in the gastrointestinal tract, these neutrophils migrate to the inflamed area and release calprotectin into the intestines. Fecal calprotectin is a stable and useful marker for detecting intestinal inflammatory activity.
Measuring calprotectin in stool helps determine the presence and extent of inflammation in the intestinal lining. The test helps healthcare providers differentiate between inflammatory conditions and non-inflammatory issues that might cause similar symptoms like abdominal pain or diarrhea. This distinction is important for guiding further diagnostic steps and treatment decisions.
Understanding Calprotectin Levels
Interpreting fecal calprotectin test results involves specific reference ranges. A level below 50 micrograms per gram (µg/g) is considered normal, indicating little to no intestinal inflammation. This low level suggests that symptoms are likely not due to an inflammatory condition.
Levels between 50 and 200 µg/g are considered borderline or moderately elevated, suggesting mild inflammation. A healthcare provider might recommend repeating the test in several weeks if symptoms persist. Levels exceeding 200 µg/g indicate significant intestinal inflammation.
Calprotectin and Cancer Detection
While elevated calprotectin levels can be observed in some gastrointestinal cancers, such as colorectal cancer, it is not a direct diagnostic marker for malignancy. The increase in calprotectin in these cases is due to the inflammatory response surrounding the cancerous tissue, rather than the cancer itself. Therefore, a high calprotectin level alone does not automatically signify cancer.
The primary utility of fecal calprotectin testing is to distinguish between inflammatory bowel diseases (IBD) and non-inflammatory conditions like irritable bowel syndrome (IBS). Calprotectin levels are typically normal in IBS but are often significantly elevated in IBD. By indicating the presence or absence of inflammation, the test can help determine if further, more invasive investigations, such as a colonoscopy, are necessary. This screening capability can help avoid unnecessary procedures for individuals whose symptoms are not caused by inflammation.
Conditions That Elevate Calprotectin
Elevated calprotectin levels are a sensitive indicator of intestinal inflammation, but they are not specific to a single condition. Inflammatory Bowel Disease (IBD), encompassing Crohn’s disease and ulcerative colitis, is a common cause of significantly elevated calprotectin, with levels often correlating with disease severity.
Beyond IBD, various gastrointestinal infections, including those caused by bacteria, viruses, or parasites, can also raise calprotectin levels due to the inflammatory response they trigger. Other conditions that may lead to elevated calprotectin include diverticulitis, microscopic colitis, and celiac disease. Certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or aspirin, can cause intestinal irritation and result in increased calprotectin levels.
Next Steps After an Elevated Calprotectin Result
An elevated fecal calprotectin result indicates intestinal inflammation and typically warrants further medical evaluation. A healthcare professional, often a gastroenterologist, will consider the patient’s symptoms, medical history, and the calprotectin level to determine the appropriate next steps.
These follow-up actions commonly include additional diagnostic tests to identify the underlying cause of the inflammation. Such tests might involve a colonoscopy with biopsies to visualize the intestinal lining and obtain tissue samples, or other imaging studies. The calprotectin test serves as a guide for clinical decisions, helping to prioritize individuals who need further investigation while potentially sparing others from unnecessary invasive procedures. Regular monitoring with repeat calprotectin tests may also track the response to treatment or assess disease activity over time.