Fecal Calprotectin (Calprotectin) Test
What is Calprotectin / Calprotectin in Feces?
Generally Calprotectin is a protein marker found in stool when intestinal inflammation occurs. Fecal Calprotectin testing helps improve patient care and save money on treatment. In many patients, those with Irritable Bowel Syndrome (IBS) are screened, eliminating the need for unnecessary endoscopy procedures.
The symptoms of functional disorders such as Irritable Bowel Syndrome (IBS) and Organic Inflammatory Bowel Disease (IBD) may be very similar at presentation, but they are two very different medical conditions.
Historically, clinical gastroenterologists have had to use invasive endoscopy to differentiate between these conditions. Clinical investigators recommend that stool calprotectin analysis be used as a first-line test in patients presenting with gastrointestinal symptoms suggestive of Irritable Bowel Syndrome (IBS) or Inflammatory Bowel Disease (IBD). The test can rule out Inflammatory Bowel Disease (IBD) and prevent Irritable Bowel Syndrome (IBS) patients from undergoing endoscopy. This avoids patient stress, shortens examination lists and reduces costs.
Calprotectin has also been shown to be of value in the ongoing evaluation of patients with IBD whose known biomarker concentration reflects mucosal healing or potential relapse.
Fecal Calprotectin is a calcium and zinc binding protein that, although found at low levels in other phagocytic cells, can be considered neutrophil-specific for practical purposes. Calprotectin accounts for approximately 60% of the total soluble proteins in the cytosol fraction of neutrophils. Neutrophils are common effector cells that define acute inflammation in response to various factors. After the neutrophil has migrated to a site of chemoattribution, contact produces a series of events that result in respiratory burst, oxygen radical generation, and the release of cytosolic granules of the neutrophil (and calprotectin); this is a variety of hydrolytic and proteolytic enzymes. In this way, the neutrophil deals with the chemoattractant, but also randomly damages its surroundings. The amount of calprotetin reflects the number of neutrophils involved in this inflammation. Adequately confirmed by significant correlation between fecal calprotectin levels and other measures of acute inflammation in IBD (indium-labeled white cell excretion or quantitative histopathological assessment of inflammation in colon biopsies in controls and individuals with ulcerative colitis. Correlation with histology in Crohn’s disease is not a problem with calprotectein, Slightly more unsatisfactory due to the patchy nature of crohn’s disease and the lack of histological evaluation of the small intestine.Important aspects with calproetectin are that it is highly resistant to degradation by intestinal pancreatic secretions, intestinal proteases and bacterial degradation and is stable in stools at room temperature for at least one week. The amount of calprotectin in feces is a noninvasive quantitative measure of neutrophil flux in the gut.
How to Measure Calprotectin in Stool?
The most common method of stool sampling is with a non-sterile tube with a small spoon in the lid. Calprotectin is then evaluated by enzyme-linked immunosorbent assay (ELISA) of a stool sample of less than 1 g. It is important to note that there are many manufacturers of ELISA kits, and they all use different antibodies and extraction media, which can cause differences in the normal range of the test, which may include sensitivity of the test. ELISA kits, including quality controls, typically use 80 to 100 cells for measurement and all samples are analyzed in duplicate. Even if clinicians do not accept the strengths and weaknesses of different assays and the reliability of the various kits available on the market, the kits are subjected to rigorous quality control measures by our laboratory experts.
It is important to note that the normal ranges reported with use of the first calprotectin kit are often extrapolated to newer kits which may cause confusion as kits from different manufacturers are different, and that the normal calprotectin ranges differ. In ancient times there was a time when the batch had to be discarded due to quality control issues. However, quality control is so rigorous that false positive or negative results are usually not a problem. If such results occur, it is most likely due to biological changes in the intensity of inflammation or the inability to mix calprotectin with feces.
A recent effort has been made to commercialize home-based spot tests that allow patients, including those with Inflammatory Bowel Disease (IBD), to extract the sample at home using a simple sampling device. If the patients had the application on their smartphones, results could be obtained within hours; Thus, the sample can be analyzed centrally. This prevents patients from going to the hospital and can speed up treatment if needed, as results are immediate. However, the reliability of this method depends on the manufacturer. However, nowadays, the samples are brought to our laboratories by the relatives of the patients and the results can be obtained online.
What Is Considered as Abnormal Concentration of Calprotectin in Stool?
When using Inflammatory Bowel Disease (IBD) quantitative testing, most studies report that the normal range will be 10 to 50 or 60 µg/mg. However, as noted above, many laboratories use historical data from the first calprotectin kit from abroad. In contrast, the normal range of calprotectin in developing countries with poor sanitation and frequent intestinal infections (which may be perceived as normal in populations) may be much higher, thus limiting the use of the test. Values from 50 µg/mg to 60 µg/mg (depending on which kit is used) are generally considered abnormal, although values as high as 100 µg/mg may be normal in some kits. For example, for screening purposes in London, values between 50 and 200 ug/mg are considered normal, especially in people of African-Caribbean descent, with the test appearing to be higher than the normal limit. In this range, doctors often suggest that individuals retest after a few weeks and that there is no need to investigate the height. If a patient’s calprotectin level is consistently mildly elevated, the rush for investigation continues as the probability of abnormal pathology is low. However, levels above 200 µg/mg have a higher positive predictive value for pathology, and values of 500-600 µg/mg almost guarantee signs of pathology.
It is important to keep in mind that fecal heartectin is inflammation and not disease specific. Almost every intestinal disease and many small bowel diseases are associated with inflammation and thus test positive for calprotectin. However, although most of these diseases are associated with low-grade inflammation such as non-steroidal anti-inflammatory drug enteropathy, calprotectin values above 500 to 600 μg/mg are overly predictive of Inflammatory Bowel Disease (IBD) or food infections. However, there is no fixed rule for calprotectin values. As clinicians use the calprotectin test more frequently, they are improving in evaluating test results in relation to patients’ symptoms.
What is the Sensitivity and Specificity of Calprotectin in Stool for the Diagnosis of Inflammatory Bowel Disease ( IBD )?
Inflammatory Bowel Disease (IBD) as previously mentioned, the fecal calprotectin test is a functional quantitative measure of intestinal inflammation and is not specific to inflammation or disease. It is usually a test that clinically supplements the endoscopy and can sometimes modify the procedure. fecal calpectin certainly has the potential to serve as a diagnostic test (rather than just a diagnostic test). An abnormal test result simply indicates intestinal inflammation of any cause. There are numerous bowel diseases and drugs (eg, NSAIDs, alcohol) associated with low-quality intestinal inflammation, with an average calprotectin level of 50-300 μg/mg. However, only untreated Inflammatory Bowel Disease (IBD) and some food infections have very high rates. Considering, for example, a range of clinical disease activity, Crohn’s colitis and small bowel Crohn’s disease draw attention to the slightly lower calprotectin. This is consistent with the fact that the small intestinal bacterial load (the main neutrophil chemoattractant) is much less than that of the colon and is thus reflected by a less intense inflammatory response. This is also reflected histologically.
The common clinical scenario in which internists and gastroenterologists use fecal calprotectin, the majority of patients presenting with gastrointestinal symptoms that may indicate irritable bowel syndrome (IBS) or Inflammatory Bowel Disease (IBD) are young patients. No doctor wants to miss out on this final diagnosis because it has lifelong implications for the patient and requires targeted therapy. Approximately 99% of patients with active IBSH have elevated fecal calprotectin levels. Also, between 15% and 20% of patients with Irritable Bowel Syndrome have slightly elevated calprotectin levels. (It is important to note that patients with postinfectious or postdiverticulitis irritable bowel syndrome-like symptoms may have been included in these studies and that these diseases are different from conventional irritable bowel syndrome.) The sensitivity and specificity of the calprotectin test for the identification of irritable bowel syndrome or IBD Different degrees of inflammation can be calculated by methods, but this information is not particularly useful clinically. Rather, the take-home message is that a normal calprotectin level is much more likely to represent irritable bowel syndrome. Therefore, the message to general practitioners is not to refer these patients to gastroenterologists who often perform endoscopy, but to gastroenterologists who see these patients to treat irritable bowel syndrome (IBS) and not to continue with endoscopy.
When is Calprotectin in Stool a Test to Replace Endoscopy in Patients with IBD?
There are several situations where fecal calprotectin is useful in established cases of Inflammatory Bowel Disease (IBD), which often provides data that complements endoscopy and sometimes provides data that endoscopy cannot. The most prominent example of the use of fecal calpectin concerns patients with increasing clinical symptoms consistent with clinical relapse of Inflammatory Bowel Disease (IBD). Instruments such as colonoscopy or capsule enteroscopy may be used in most of these cases, but an ulcer can be found without much inflammation (ie rectal ulcer alone). However, it is clear that clinical symptoms, and especially clinical recurrence of disease, are associated with intestinal inflammatory activity; this is exactly the information that calprosthesis testing provides. Given that a patient in this scenario has a very high calprotectin level, there is little justification for using an invasive procedure instead, and acute treatment can be safely provided in the majority of cases. However, if this treatment does not work, alternative causes of symptoms should be sought.
However, if a symptomatic IBD patient has a normal or near-normal calprotectin level, is it safe to assume that the symptoms are not due to Inflammatory Bowel Disease (IBD) in most cases? On average, some patients with very limited proctitis (where there is little mixing with inflammatory exudate with stool) and small bowel Crohn’s disease have lower calprotectin levels than patients with Inflammatory Bowel Disease (IBD) colitis with similar clinical disease activity. In addition, patients with Crohn’s disease may have alternative explanations for their symptoms, such as strictures and fistulas. As with any test, the usual recommendations are to consider the overall clinical picture, not to rely on a single clinical or laboratory measure.
Can Stool Calprotectin Predict Clinical Relapse of Inflammatory Bowel Disease (IBD)?
Fecal Calprotectin can predict close clinical recurrence with 80% sensitivity and accuracy in patients with relatively asymptomatic IBD (ulcerative colitis or Crohn’s disease). A patient with asymptomatic irritable bowel syndrome with a high calprotectin level will have an 80% chance of clinical relapse within the next 6 months, whereas only 20% of patients with low calprotectin levels will experience clinical relapse. In this context, the exact cut-off value for the distinction between high and low calprotectin levels varies. Our colleagues’ data and we suggest a cutoff of 250 μg/mg, but other researchers have suggested a slightly lower cutoff using receiver operating characteristic curve analyses. A study using leukocyte aphaeresis showed that treatment at this asymptomatic stage can prevent clinical relapse. It is also possible that simpler treatment, such as a dose increase of 5-aminosalicylates or a short dilution of corticosteroids, could have the same effect, but this has not yet been studied. Avoiding clinical recurrence is an important issue in IBD because of the accompanying morbidity and deterioration in quality of life.
Does Fecal Calprotectin Have a Role in Predicting Mucosal Healing?
New therapeutic agents for the treatment of Inflammatory Bowel Disease (IBD) have created a wave of excitement not only because of their effectiveness and acceptable side effects, but also because of the possibility of achieving mucosal healing. The definition of mucosal healing differs between different studies and there is no universally accepted definition. Most clinical studies describe mucosal healing based on endoscopy and biopsy specimens. This definition applies to colonoscopist trials and gastroenterologists, but is not practical in clinical practice with limited resources. If mucosal healing is defined as the absence of significant acute inflammation, this result can be assessed with a stool calprotectin test representative of the entire gut, rather than small biopsy samples that will not reflect the rest of the gut.
How to Predict the Response of Calprotectin in Stool to Treatment
While the utility of measuring fecal calprotectin is evident in its increasing use in clinical trials, the primary endpoints are still symptom-based. Gastroenterologists should follow the example of rheumatologists who change therapy based on markers of inflammation rather than patients’ symptoms. This resulted in a beneficial change in the natural cured disease history.
Similarly, measuring calprotectin levels during the treatment of acute relapse of the disease is that the treatment is working and the symptoms are relaxed, not masked. This may not be necessary in most patients, but there is good data to show that normal calprotectin levels can be delayed or stopped immediately prior to routine administration of a biologic agent. However, much more research needs to be done before a firm decision can be made as to whether this approach is safe.
In Crohn’s disease with symptomatic obstruction, the obstructive manifestations may be due to a fibrous stricture or an inflammatory component. An elevated stool calprotectin level will then help determine treatment: surgery for the former cause but aggressive medical treatment for the latter. Again, there is a lack of clinical data on this subject, but until research is done, common sense should prevail.
In addition, patients with Inflammatory Bowel Disease ( IBD ) are often placed on long-term 5-aminosalicylate therapy, which has been shown to reduce the frequency and severity of clinical relapses. Most patients, especially those with ulcerative colitis, take a fixed daily dose. Fecal calprotectin can identify patients who have normal calprotectin levels and do not require maintenance therapy. Similarly, as above, high-level patients may benefit from an increase in therapeutic dose.
Can Post-Surgical Calprotectin Levels Predict Crohn’s Disease Relapse?
This is a problem especially after right hemicolectomy for small bowel Crohn’s disease, where the surgeon may consider that the volume of the disease has been removed, if not all. Today, recurrence is often defined as anastomotic disease in symptomatic individuals. However, recurrence of Crohn’s disease needs a better definition than this. My colleagues and I measure calprotetin levels several months after surgery and every 4-6 months thereafter, looking for a significant increase indicative of new disease. It is very important to perform a capsule enteroscopy shortly after the operation, as this procedure will help determine whether residual disease is present. This may affect the patient’s prognosis and can be medically controlled (not studied) to alter the natural history of the disease. Normal calprotectin levels and capsule images may be prognostically favorable indicators (not studied). Such studies require multicenter collaboration and highlight the potential use of calprotectin in Inflammatory Bowel Disease (IBD).
Does Fecal Calprotectin Have a Role in Pouch Inflammation?
Fecal Calprotectin is also useful for detecting the acute inflammatory component that causes cachexia (weakness/weakness). However, there are few (if any) studies showing that calprotectin level is well correlated with clinical symptoms, although there is usually significant correlation with the histopathological assessment of acute inflammation. The problem may be very localized inflammation of patients with symptomatic pouches, which adds to the urgency and frequency of bowel openings, and the calprotectin test may be inferior to pouchoscopy under these circumstances.
How to Use Fecal Calprotectin in Costly IBD ?
No formal cost-effectiveness analysis has been done to date, but we know that costs are significant in both general practice and hospitals. The number of false negative results in IBSH patients is negligible, and only very elderly patients seem to have problems with sample collection. Additionally, stool calprotectin testing sometimes allows patients to avoid endoscopic procedures that are more expensive than testing.
Fecal Calprotectin is studied with 2 different techniques in Istanbul Laboratories;
– Blue Tech Method – Measures up to 300
– High Range Method – Measures up to 1500 – 2000
If your values are very high when you apply to our laboratory, please state that you want to have a test with the Height range method.