Diagnostic tests for UC may include a serology (blood) test panel that checks for specific antibodies. These may help doctors distinguish between UC and Crohn’s disease.
Ulcerative colitis (UC) and Crohn’s disease are the two main types of inflammatory bowel disease (IBD). Doctors typically diagnose IBD through a combination of imaging tests, blood tests, and symptom and family history. Another diagnostic tool — antibody tests — can help distinguish between UC and Crohn’s disease.
With UC, your immune system mistakenly attacks tissues that line your large intestine, causing inflammation and ulcers. This condition can develop gradually or sometimes suddenly. Most people receive a diagnosis before
If you’re currently undergoing testing for UC or suspect you might be experiencing symptoms of this type of IBD, consider talking with a doctor about how antibody tests may help diagnose and treat this condition.
Antibody testing helps doctors diagnose UC in two ways.
First, the presence of antibodies may confirm findings from other UC diagnostic tests. Your immune system produces antibodies in response to certain diseases, like UC. Having specific antibodies, or biomarkers, in your blood typically suggests the presence of a disease.
Second, antibody testing can help distinguish between UC and Crohn’s disease when other diagnostic tests may not. For example, while a biopsy or an imaging test of the large intestine can detect inflammation, it may not be enough to determine the type of IBD.
There are several different antibodies present in people with UC. But most of these aren’t present in a majority of people with UC. They’re also often present in people with Crohn’s disease — with one exception.
Perinuclear antineutrophil cytoplasmic antibodies (pANCA) are present in
Another type of antibody seen in IBD is called anti-Saccharomyces cerevisiae antibody (ASCA). It’s present in
Anti-integrin alpha-v beta-6 (αvβ6) autoantibodies may also be present in people with UC, though doctors don’t test for these as often as pANCA.
Antibody testing can help diagnose UC, but it’s not 100% accurate. It’s still possible to have UC and not test positive for pANCA. On the flip side, it’s also possible to have UC but test positive for ASCA.
In a small
The study also found that testing positive for pANCA and negative for ASCA was the best way to tell UC apart from Crohn’s disease.
What conditions may cause you to be positive for ANCA?
Doctors can use antineutrophil cytoplasmic antibodies (ANCA) tests to check for systemic vasculitis (inflammation in your blood vessels) or UC.
There are two types of ANCA: perinuclear (pANCA) and cytoplasmic (cANCA).
The presence of pANCA may indicate UC, but it could also be a sign of a rare type of vasculitis called microscopic polyangiitis.
The presence of cANCA may suggest a type of vasculitis called granulomatosis with polyangiitis (GPA).
A pANCA antibody test for UC is a blood test. During the test, a technician or nurse will draw blood from a vein in your arm via a needle. They collect a small sample in a vial and then send it to a lab for testing. The sample collection should take no longer than 5 minutes.
Once at the lab, a technician will run the blood sample through a machine that looks for antibodies. The presence of antibodies could yield a positive test result. A negative result means they found no antibodies.
It’s unclear whether pANCA antibodies can predict the future development of UC. Certain blood tests may help predict the severity of Crohn’s disease complications, but not for Crohn’s disease itself.
But emerging research suggests that anti-integrin αvβ6 autoantibodies could potentially predict UC. One 2023 study found that anti-integrin αvβ6 antibodies could precede UC by as much as 10 years.
For an accurate diagnosis, doctors consider the results of antibody testing with other tests for UC. These may include:
- X-rays: Traditional X-rays can provide images of inflammation in your intestines.
- CT scan: These are more detailed versions of X-rays that may help differentiate between UC, bowel blockage, and appendicitis.
- Endoscopy: Doctors use a small tube to take pictures of your gastrointestinal (GI) tract.
- Biopsy: Often combined with an endoscopy, this involves taking a small tissue sample from your large intestine for testing.
- White blood cell scan: This imaging test detects where white blood cells might gather inside the GI tract, indicating where inflammation may occur.
- Liver function tests: These blood tests may detect issues with your liver or bile duct that may be related to UC.
- Other blood tests: The following tests may help detect underlying inflammation:
- Stool tests: These can help detect large intestinal inflammation and may also help rule out other conditions that may be causing your symptoms, such as infections.
Antibody testing for UC may help detect certain substances in your blood that could indicate issues with your immune system attacking healthy cells in your large intestine.
However, antibody tests are just one of the many diagnostic tools a doctor may consider for possible UC. These can complement other tests, such as imaging and biopsy, and help clarify what type of IBD you may have.