What is a calprotectin stool test?

A calprotectin stool test measures a protein called calprotectin in a sample of your stool (poop). The test is also called a fecal calprotectin test. It's used to check for inflammation (swelling and irritation) in your intestines.

It's normal to have a small amount of calprotectin in your stool. But high levels are a sign that your intestines are inflamed. When you have inflammation in your intestines, your immune system sends certain types of white blood cells (neutrophils) to the inflamed area. These white blood cells release calprotectin into your intestines where it mixes with your stool.

Inflammation in your intestines can cause severe watery or bloody diarrhea with abdominal (belly) pain and/or cramping that last for more than a few days. Other types of digestive conditions can also cause these symptoms. If these symptoms last a long time or come and go, it's important to know if your intestines are inflamed. That's because inflammation can damage the lining of your intestines and lead to other serious health conditions over time.

A calprotectin test can find out whether your intestinal condition involves inflammation. But it can't diagnose the specific cause. Knowing whether your intestines are inflamed helps your health care provider decide what other tests you may need and what treatments are best for you.

Other names: Fecal calprotectin

What is it used for?

Calprotectin stool testing is used to check for inflammation in the intestines. In most cases, providers use calprotectin stool testing to help tell the difference between inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS).

IBD and IBS are both chronic (long-lasting) conditions that affect adults and children. They cause similar symptoms that can come and go, including diarrhea, belly pain, and cramps. But only IBD involves inflammation:

• IBD is a group of digestive diseases. It may cause watery and/or bloody diarrhea. Over time, inflammation from IBD damages the lining of the intestines. Symptoms may disappear for weeks or years and then come back. Experts think IBD may have many causes, including autoimmune disorders and genes. The main types of IBD are:
  • Crohn's disease
  • Ulcerative colitis
• IBS is a group of symptoms that happen together. They include bloating, pain and/or cramps when you have bowel movements, and diarrhea, constipation, or both. Researchers think IBS may be caused by a problem with how your brain and intestines (gut) work together. IBS does not damage your intestines and tests do not show inflammation.

Depending on your symptoms and medical history, a calprotectin in stool test may be used with other stool tests that can help find the cause of long-lasting diarrhea. These include tests for fecal occult blood, bacteria in stool, parasites and eggs, and/or a white blood cell (WBC) in stool test.

If a person has been diagnosed with IBD, a calprotectin stool test may be used to help:

• Find out how severe the inflammation is
• Guide treatment choices
• Check to see if IBD is getting better or worse
• Predict the chance that IBD symptoms will return, including after surgery to treat IBD

Why do I need a calprotectin stool test?

Most watery diarrhea goes away on its own after a day or two, and your provider doesn't need to do tests. But if your symptoms don't improve after a few days or keep coming back, you may need a calprotectin stool test to check for inflammation in your intestines.

Along with diarrhea, belly pain and cramping, other symptoms of inflammation in your intestines may include:

• Blood, mucus, and/or pus in your stool. Contact your provider right away if you see blood or pus in your stool, or if your stool is black and tarry.
• Always feeling like you need to move your bowels (poop) even when there's no stool. This condition may be painful and cause cramps.
• Feeling an urgent need to move your bowels.
• Weight loss when you're not trying to lose weight.

If you already have IBD, you may need calprotectin testing to monitor your condition. This information helps your provider choose treatment and check whether it's working.

What happens during a calprotectin stool test?

You will need to provide a stool sample for your test. Your provider will probably give you a container or kit with instructions on how to collect the sample. There are different ways to collect stool samples, so follow the instructions carefully. In general, you'll need to:

• Label the container with your name, the collection date, and time.
• Collect a stool sample as instructed. This usually involves using a clean, dry container, or special paper or plastic wrap placed over the toilet to catch the stool.
• Make sure the stool doesn't mix with any urine (pee), toilet paper, or water from the toilet.
• Close the container tightly.
• Wash your hands well with soap and water.
• Return the container according to the instructions.

If you're collecting a sample from diapers, you'll get special instructions for using plastic wrap inside of a clean diaper. In certain cases, a provider may use a swab to take a stool sample from the rectum.

Will I need to do anything to prepare for the test?

Ask your provider if you need to stop taking any medicines before your test. But never stop taking any medicine without talking with your provider first. Medicines that may affect your test results include certain over-the-counter medicines, including:

• Nonsteroidal anti-inflammatory drugs (NSAIDs), which are used to relieve pain. Examples include aspirin, ibuprofen, and naproxen.
• Proton pump inhibitors (PPIs), which are used to control stomach acid and relieve symptoms of GERD. Examples include omeprazole, esomeprazole, and lansoprazole.

Are there any risks to the test?

There is no known risk to having a calprotectin stool test.

What do the results mean?

Normal or low levels of calprotectin usually mean that your intestines are not inflamed, which means you don't have inflammatory bowel disease (IBD). Your symptoms are probably caused by a type of non-inflammatory condition. Your provider may order other tests to figure out which condition is causing your symptoms.

But it's possible to have normal calprotectin test results even when your intestines are inflamed. This is called a "false negative." False negative calprotectin results mostly happen in children.

High levels of calprotectin usually mean that your intestines are inflamed. The higher the amount of calprotectin in your stool, the more inflammation you have. If your calprotectin levels are high, your provider may retest you in a few weeks to see if they change.

Several conditions can cause high calprotectin levels, so you may need other tests to find the cause. In general:

• Very high levels of calprotectin are often linked to:
  • Inflammatory bowel disease (IBD)
  • Food poisoning caused by certain types of bacteria
• Somewhat high levels of calprotectin are often linked to:
  • Intestinal or colorectal cancer
  • Celiac disease
  • Certain bacterial infections in your intestines, such as Clostridium difficile (C. diff)
  • Taking NSAIDs
  • IBD that has been treated

If your calprotectin test results show that your intestines are inflamed, your provider may order a colonoscopy, which uses a tiny camera to look inside your intestines. This helps your provider learn whether IBD or another condition is causing the inflammation. But if your calprotectin test results show that your intestines probably aren't inflamed, a colonoscopy is unlikely to help make a diagnosis. In this way, a calprotectin stool test can help avoid unnecessary colonoscopies.

If you have questions about your test results, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a calprotectin stool test?

If your provider thinks you could have IBD, you may first have a blood test to check for inflammation. The blood test may be a C-reactive protein (CRP) test or an erythrocyte sedimentation rate (ESR) test. But a calprotectin stool test is more accurate at finding inflammation in the intestines.