Crohn’s disease is a chronic inflammatory bowel disease (IBD) that can affect any part of the digestive tract, from the mouth to the anus. This condition causes long-term inflammation, leading to symptoms such as abdominal pain, severe diarrhea, fatigue, and weight loss. Managing Crohn’s disease often involves monitoring inflammation non-invasively, and the faecal calprotectin test serves as a valuable tool in this process. This article explores the role of this test and what its results signify for individuals living with Crohn’s disease.
What is Faecal Calprotectin?
Faecal calprotectin is a protein released primarily by neutrophils, a type of white blood cell involved in the body’s immune response. When inflammation occurs in the gastrointestinal tract, neutrophils migrate to the affected areas. These activated neutrophils then release their contents, including calprotectin, into the intestinal lumen.
The calprotectin released remains stable and is not degraded as it passes through the digestive system, allowing it to be detected in stool samples. Elevated calprotectin levels in stool indicate inflammation within the intestines. This makes it a useful biomarker for identifying inflammatory conditions like Crohn’s disease, reflecting ongoing immune activity in the gut.
Interpreting Faecal Calprotectin Test Results
Faecal calprotectin test results are typically reported in micrograms per gram (µg/g) of stool, with different ranges indicating varying degrees of intestinal inflammation. A low level, generally less than 50 µg/g, suggests no significant intestinal inflammation. Such a result often indicates a patient with Crohn’s disease is in clinical remission, meaning their disease is inactive.
Borderline or intermediate levels, ranging from 50 to 200 µg/g, can indicate mild inflammation or warrant further investigation. Healthcare providers might recommend re-testing or other diagnostic approaches. High levels, exceeding 200 µg/g, suggest active inflammation within the gastrointestinal tract. These elevated values are consistent with a Crohn’s disease flare-up, indicating increased disease activity. Reference ranges can vary between laboratories, so results should always be interpreted with a patient’s overall clinical presentation and healthcare provider’s guidance.
Role in Monitoring Crohn’s Disease Activity
The faecal calprotectin test is a valuable tool for the long-term management of Crohn’s disease, extending beyond a single measurement. Regularly monitoring calprotectin levels provides insights into disease progression and treatment effectiveness. When patients begin a new therapy, a subsequent drop in levels indicates the treatment is reducing intestinal inflammation. This objective measure helps confirm medication efficacy.
Rising calprotectin levels in a patient who may otherwise feel well can serve as an early warning sign of a disease relapse or flare-up. This allows healthcare providers to consider proactive adjustments to treatment strategies before symptoms become severe, potentially preventing complications. Consistently low faecal calprotectin levels also help confirm mucosal healing, which refers to the healing of the gut lining, a significant goal in Crohn’s management. Achieving and maintaining mucosal healing, often more reliably indicated by calprotectin than by symptoms alone, is associated with better long-term outcomes and a reduced need for surgery.
Differentiating Crohn’s from Non-Inflammatory Bowel Conditions
The faecal calprotectin test helps clinicians distinguish between inflammatory bowel diseases like Crohn’s and non-inflammatory conditions. Irritable Bowel Syndrome (IBS) presents with symptoms similar to Crohn’s, such as abdominal pain, cramping, and changes in bowel habits. However, IBS is a functional disorder that does not cause inflammation in the gastrointestinal tract.
Individuals with IBS have normal or low faecal calprotectin levels. This distinction makes the test useful for healthcare providers when evaluating patients experiencing digestive symptoms. A normal calprotectin result can help a clinician determine symptoms are unlikely to be caused by inflammatory bowel disease, potentially avoiding more invasive and costly procedures like a colonoscopy. The test therefore helps guide diagnostic pathways, ensuring appropriate and timely interventions.
Factors Influencing Calprotectin Levels
While faecal calprotectin is a reliable marker for intestinal inflammation, other factors unrelated to Crohn’s disease activity can also lead to elevated levels. Non-steroidal anti-inflammatory drugs (NSAIDs) can cause mild gut inflammation and transiently raise calprotectin levels. Gastrointestinal infections also trigger an inflammatory response that can result in elevated calprotectin.
Other forms of inflammatory bowel disease, particularly ulcerative colitis, also show high calprotectin levels. Less common causes that can elevate calprotectin include celiac disease and colorectal cancer. An elevated faecal calprotectin level should always be interpreted within the clinical context of the patient, considering all influencing factors alongside their symptoms and medical history.