Calprotectin is a protein found in neutrophil granulocytes, a type of white blood cell. Its concentration in feces (stool) can indicate the presence of neutrophils in the intestines, which often signifies inflammation. Therefore, fecal calprotectin is a non-invasive marker used primarily to detect and monitor inflammation in the intestines.
Here’s when fecal calprotectin measurement is useful:
- Differentiating IBS from IBD: One of the primary uses of fecal calprotectin testing is to help differentiate between inflammatory bowel disease (IBD) such as Crohn’s disease or ulcerative colitis, and irritable bowel syndrome (IBS). IBS does not involve intestinal inflammation, whereas IBD does. Thus, elevated calprotectin levels are more suggestive of IBD, while normal levels are more consistent with IBS.
- Monitoring IBD Activity: In individuals diagnosed with IBD, fecal calprotectin levels can help assess the severity of inflammation and monitor the response to treatment. An increase in fecal calprotectin levels might indicate a flare or worsening of the disease, while decreasing levels may suggest improvement or remission.
- Predicting Relapse: In IBD patients in remission, a rising calprotectin level might indicate an impending relapse even before symptoms appear.
- Screening Tool: While endoscopy with biopsy is the gold standard for diagnosing IBD, it’s invasive and costly. Measuring fecal calprotectin can act as a screening tool to decide who might benefit from further invasive testing.
- Monitoring Post-surgical Recurrence: In patients with IBD who have undergone surgical interventions, fecal calprotectin can help monitor for recurrence of disease post-surgery.
- Other Inflammatory Conditions: Elevated fecal calprotectin can also be seen in other conditions like colorectal cancer, infections, and nonsteroidal anti-inflammatory drug (NSAID) use, though it’s primarily used in the context of suspected or known IBD.
Limitations:
- Fecal calprotectin is a sensitive but non-specific marker. Elevated levels can be seen in various conditions, so clinical context is essential.
- Factors like NSAID use, infections, or even some foods can elevate fecal calprotectin levels.
- It’s essential to correlate the test results with clinical symptoms and other investigations.
Given its non-invasive nature and relatively low cost compared to procedures like endoscopy, fecal calprotectin is a valuable tool in specific clinical contexts, especially concerning gastrointestinal disorders.