Also known as:Fecal Calprotectin; Stool Calprotectin
Related tests:Lactoferrin, Fecal Occult Blood Test and Fecal Immunochemical Test, Stool Culture, Stool White Blood Cell, Clostridium difficile and C. difficile Toxin Testing, ESR, C-Reactive Protein
Why Get Tested?
To detect inflammation in the intestines; to distinguish between inflammatory bowel disease (IBD) and non-inflammatory bowel conditions; to monitor IBD activity
When to Get Tested?
When you have bloody or watery diarrhea, abdominal cramps, with or without fever, lasting more than a few days
A stool sample collected in a clean container
Test Preparation Needed?
How is it used?
Calprotectin is a stool (fecal) test that is used to detect inflammation in the intestines. Intestinal inflammation is associated with, for example, some bacterial infections and, in people with inflammatory bowel disease (IBD), it is associated with disease activity and severity. The calprotectin test is not diagnostic but may be used to distinguish between IBD and non-inflammatory disorders and to monitor IBD disease activity.
A doctor may order calprotectin to help investigate the cause of a person's persistent watery or bloody diarrhea. The test may be ordered along with other stool tests, such as a stool culture to detect a bacterial infection, a stool white blood cell test, and/or a fecal occult blood test (FOBT). If a doctor suspects inflammation, then blood tests that detect inflammation in the body, such as an erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP), may also be ordered. Testing is performed both to help determine what is causing a person's symptoms and to rule out conditions with similar symptoms. This means that additional blood and stool testing may be performed depending on the suspected causes.
A calprotectin test may be ordered to help determine whether an endoscopy is indicated if IBD is suspected. A diagnosis of IBD is usually confirmed by performing an endoscopy (colonoscopy or sigmoidoscopy) to examine the intestines and by obtaining a small tissue sample (biopsy) to evaluate for inflammation and changes in tissue structures. This testing is invasive and is less likely to be necessary if inflammation is not present.
A calprotectin test may be ordered if a person with IBD has symptoms that suggest a flare-up, both to detect disease activity and to help evaluate its severity. For example, if a person has a moderately elevated calprotectin, then testing may be repeated several weeks later to see if it has stayed moderately elevated, increased, or returned to normal.
When is it ordered?
A calprotectin test may be ordered when a person has symptoms that suggest that gastrointestinal inflammation may be present and when a doctor wants to distinguish between IBD and a non-inflammatory bowel condition.
Symptoms will vary from person to person and over time. They may include one or more of the following:
- Bloody or watery diarrhea
- Abdominal cramps or pain
- Weight loss
- Rectal bleeding
Testing for calprotectin may be performed when a doctor wants to determine whether an endoscopy (colonoscopy or sigmoidoscopy) is likely or less likely to be necessary.
When a person has been diagnosed with IBD, a calprotectin test may be ordered whenever a flare-up is suspected, both to confirm disease activity and to evaluate its severity.
What does the test result mean?
An elevated calprotectin indicates that inflammation is likely present in the gastrointestinal tract but does not indicate either its location or cause. In general, the degree of elevation is associated with the severity of the inflammation.
Increases in calprotectin are seen with IBD, but also with bacterial infections, some parasitic infections, and with colorectal cancer. An endoscopy (colonoscopy or sigmoidoscopy) may be indicated as a follow-up test to help determine the cause of inflammation, signs, and symptoms.
In people newly diagnosed with IBD, concentrations of calprotectin may be very high.
A low calprotectin means that signs and symptoms are likely due to a non-inflammatory bowel disorder. Examples of these include irritable bowel syndrome (IBS) and viral gastrointestinal infections. In people with low calprotectin results, an endoscopy is less likely to be indicated or useful.
A moderate calprotectin level may indicate that there is some inflammation present or that a person's condition is worsening. A repeated calprotectin test with a result that is still moderately elevated or that has increased is likely to require further investigation and may warrant an endoscopy.
Is there anything else I should know?
Anything that causes inflammation in the intestines can cause an increase in stool calprotectin.
Calprotectin can be increased with the intestinal tissue damage and bleeding that is sometimes seen with use of non-steroidal anti-inflammatory drugs (NSAIDs).
Calprotectin is related to another stool test, lactoferrin. Both are substances that are released by white blood cells in the stool and are associated with intestinal inflammation. The clinical use of these tests is still relatively new. They are promising as non-invasive ways of evaluating intestinal inflammation and are potentially more sensitive than stool white blood cell testing, but they are not yet available in all laboratories. Of the two tests, calprotectin has been the most extensively studied and it is ordered more frequently than lactoferrin. Usually one or the other will be ordered, but not both.
In some cases, calprotectin may be low even when inflammation is present (a false negative). This is most frequently seen with children.
What is being tested?
Calprotectin is a protein released by a type of white blood cell called a neutrophil. When there is inflammation in the gastrointestinal (GI) tract, neutrophils move to the area and release calprotectin, resulting in an increased level in the stool. This test measures the level of calprotectin in stool as a way to detect inflammation in the intestines.
Intestinal inflammation is associated with inflammatory bowel disease (IBD) and with some bacterial GI infections, but it is not associated with many other disorders that affect bowel function and cause similar symptoms. Calprotectin can be used to help distinguish between inflammatory and non-inflammatory conditions.
IBD is a group of chronic disorders characterized by inflamed and damaged tissues in the lining of the intestinal tract. The cause of IBD is not known, but these diseases are thought to be due to an autoimmune process that has been triggered by a genetic predisposition, a viral illness, and/or an environmental factor. The most common inflammatory bowel diseases are Crohn disease (CD) and ulcerative colitis (UC).
People with IBD typically have flare-ups of active disease that alternate with periods of remission. During a flare-up, a person may experience frequent bouts of watery and/or bloody diarrhea, abdominal pain, weight loss, and fever. Between these flare-ups, symptoms frequently subside. Many people may go through extended periods of remission between flare-ups. Calprotectin testing can be useful in monitoring disease activity. The test is not specific or diagnostic for IBD, but it may be done to detect and evaluate the degree of inflammation.
How is the sample collected for testing?
A stool sample is collected in a clean container provided by the laboratory. This sample should be uncontaminated by urine or water.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
- Can a blood test be substituted for a stool calprotectin test?
- What can I do to decrease my calprotectin?
Calprotectin is a reflection of gastrointestinal inflammation and is not affected by lifestyle changes. If it is due to an infection, then it will most likely return to normal when the infection resolves. If it is due to inflammatory bowel disease, then it will rise and fall with disease activity. In the rare case that an elevated calprotectin is caused by non-steroidal anti-inflammatory drug (NSAID) therapy, then it is likely to return to normal when the medication is discontinued.
- Can the calprotectin test be performed in my doctor's office?
No. This test is somewhat specialized and is not offered by all laboratories. The sample will likely be sent to a reference laboratory for testing and it many take several days before results are available.
© 2017 American Association for Clinical Chemistry, republished from Lab Tests Online.*
Descriptions of clinical laboratory tests were originally prepared for use on Lab Tests Online, an award-winning patient education website on clinical laboratory testing. Lab Tests Online is produced by the American Association for Clinical Chemistry (AACC), a global scientific and medical professional organization dedicated to clinical laboratory science and its application to healthcare. The Lab Tests Online website is developed in collaboration with other laboratory professional societies and is funded in part through corporate sponsorships.