An elevated fecal calprotectin result is a significant finding in gastrointestinal health. This simple, non-invasive test uses a stool sample to measure the concentration of a specific protein found in the feces. The measurement acts as a highly sensitive indicator of inflammation occurring within the intestines. Determining the exact cause of an elevated level helps healthcare providers differentiate between conditions requiring immediate intervention and those managed conservatively. This biomarker assessment guides the subsequent diagnostic process.
Understanding Calprotectin as an Inflammatory Marker
Calprotectin is a complex protein predominantly stored within the cytoplasm of neutrophils, which are a common type of white blood cell. Neutrophils are among the first immune cells to migrate to an area of tissue damage or infection in the body. When the lining of the gastrointestinal tract becomes inflamed, these immune cells rush to the site of injury.
As the neutrophils perform their protective function, they release their contents, including large amounts of the calprotectin protein. This protein is highly stable and resistant to degradation by digestive enzymes within the gut. Because it remains intact as it passes through the intestines, the amount of calprotectin can be accurately measured in a stool sample.
The concentration of this protein in the feces directly correlates with the number of neutrophils that have migrated into the intestinal lumen. Therefore, a high fecal calprotectin level serves as a reliable, quantitative measure of inflammation in the digestive system. It is important to recognize that this protein is only a marker of inflammation, not a specific diagnosis in itself.
Interpreting the Degree of Elevation
Test results are categorized into distinct ranges, with clinical significance increasing as the level rises above the normal threshold. A result below 50 micrograms per gram (\(\mu\)g/g) is considered normal, suggesting intestinal inflammation is unlikely to be the cause of symptoms. Low calprotectin levels often point toward non-inflammatory conditions, such as Irritable Bowel Syndrome.
Levels falling between 50 \(\mu\)g/g and approximately 200 \(\mu\)g/g are considered a gray area or mildly elevated. This range may indicate mild, transient inflammation, possibly due to a minor infection or irritation. This often necessitates a repeat test after a few weeks. Clinical evaluation is necessary in this range to determine if symptoms warrant a more immediate investigation.
When the fecal calprotectin concentration exceeds 200 \(\mu\)g/g, it strongly suggests the presence of significant intestinal inflammation. Levels this high are predictive of an organic disease process requiring further diagnostic workup. Higher concentrations indicate more extensive mucosal damage and greater severity of inflammation within the gut.
Specific Conditions That Cause High Calprotectin
The most common cause of a persistently high calprotectin level is Inflammatory Bowel Disease (IBD), which includes Crohn’s disease and ulcerative colitis. IBD is characterized by chronic inflammation and damage to the digestive tract lining. This damage triggers a continuous influx of neutrophils into the intestinal wall.
Acute gastrointestinal infections are another frequent cause of elevated calprotectin, often resulting in temporary but very high readings. Bacterial or viral gastroenteritis causes a rapid inflammatory response as the immune system works to clear the pathogen. In these cases, the calprotectin level will normalize once the infection has resolved, differentiating it from the chronic inflammation seen in IBD.
Certain medications can also induce sufficient inflammation to elevate calprotectin levels. The use of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), such as ibuprofen, can cause irritation and small ulcerations in the intestinal lining. This drug-induced injury recruits neutrophils and subsequently raises the fecal calprotectin concentration.
Other, less common gastrointestinal conditions may also lead to an elevated result. Diverticulitis, which is the inflammation of small pouches in the colon wall, can produce localized inflammation and neutrophil migration. Additionally, conditions like colorectal cancer or microscopic colitis sometimes cause enough mucosal disruption to result in a modest elevation of the protein.
Follow-Up Diagnostic Procedures
An elevated fecal calprotectin test is followed by a referral to a specialist for further evaluation to determine the precise source of inflammation. The standard procedure for confirming an organic intestinal disease is endoscopy, such as a colonoscopy or sigmoidoscopy. These procedures allow a physician to visually inspect the lining of the colon for signs of inflammation or ulceration.
During the endoscopy, small tissue samples, known as biopsies, are collected for microscopic examination to confirm the specific type of disease present. If the calprotectin level is very high, suggesting active inflammation, the need for this invasive procedure is prioritized. Conversely, a normal or mildly elevated result makes a structural disease like IBD less likely, potentially sparing the patient an unnecessary colonoscopy.
For patients already diagnosed with IBD, the fecal calprotectin test is used as a monitoring tool. Consistent testing tracks the effectiveness of ongoing treatment by showing a reduction in inflammation. It also serves as an early warning sign of a disease flare-up, allowing for timely adjustments to the medical management plan.