Can A Blood Test Detect Crohn’s Disease?

Crohn’s disease is a kind of inflammatory bowel disease or IBD that can affect the whole digestive system. It primarily affects the ileum or the end of the small intestine. However, there are also cases where other parts of the small intestine or the large intestines are affected. The most common systems of Crohn’s disease are stomach pain and diarrhea.

Blood tests are only one of the many diagnostic tests used to detect if a person has Crohn’s disease. If you show signs or symptoms, your physician will conduct many tests, including blood tests, imaging tests, stool tests, tissue biopsies, colonoscopy, or sigmoidoscopy. Blood tests can help diagnose IBD and monitor the person’s condition once they’ve been diagnosed.

Understanding Crohn’s Disease

As an inflammatory disease, Crohn’s disease is characterized by irritation of the digestive tract and other symptoms. According to, nearly 1.6 million Americans have IBD, with almost 780,000 people having Crohn’s disease. Further research is still needed about Crohn’s disease because even to this day, no one knows how the disease begins.

Researchers also don’t know who are the most at risk of developing the disease or how to manage it best. Moreover, there is still no cure for Crohn’s disease even though the past decades have seen significant advances in treatment. Crohn’s disease is a life-long condition that, although treated, cannot be cured. As such, it has a profound impact on the patient’s quality of life.

Which part of the body does Crohn’s disease affect?

Crohn’s disease most commonly affects the small intestine and the colon. However, there are some cases where the gastrointestinal tract is also affected, starting from the mouth to the anus. Sometimes, only some parts of the GI tract are affected. The severity of the disease can range from mild to debilitating.

What are the symptoms of Crohn’s disease?

Crohn’s symptoms can vary and sometimes change over time. If it is a severe case, the symptoms can be deadly and lead to complications. The symptoms often develop progressively, going worse over time. The symptoms may also develop quite suddenly, but that rarely happens. The signs that show the earliest are:

  • Fever
  • Fatigue
  • Diarrhea
  • Weight loss
  • Loss of appetite
  • Abdominal cramps
  • Blood in the stool
  • Feeling the need to release bowel frequently
  • Feeling like the bowels aren’t empty after relieving

It is possible to confuse these symptoms for other conditions such as an upset stomach or food poisoning. If the symptoms do not go away after a while, then you should quickly see a doctor and find out what’s wrong with you. As mentioned, the symptoms of Crohn’s disease become serious as it progresses. The more severe Crohn’s disease symptoms are:

  • Skin and joint inflammation
  • Shortness of breath or anemia
  • Ulcers anywhere the body, including the mouth and anus
  • Perianal fistula, which leads to drainage near the anus as well as pain

It will significantly help if it is detected and diagnosed early. This way, you start Crohn’s treatment early and avoid developing severe complications. When you start showing the early signs, it’s best to head directly to the doctor for a diagnosis. You will likely undergo several tests, including blood tests, to determine if you have Crohn’s disease.

Blood Tests That May Indicate Crohn’s Disease

There are different tests used to detect and diagnose Crohn’s disease. Blood tests are only one of them. Unfortunately, no Crohn’s blood tests can tell directly if you have the disease or any other IBD. Instead, blood tests help examine if there is inflammation in your body but doesn’t tell where it. If it finds out you have inflammation, then you can move on to try other tests.

Full Blood Count (FBC)

This is the most common blood test used in diagnosing Crohn’s disease and essentially IBD. It measures the number of blood cells and the different types of them present in your body. It can also provide an IBD diagnosis and give clues that you have the disease. Full blood count can also measure levels while you’re taking IBD medication.


In the past few years, researchers identified several antibodies to be associated with IBD. The serology test can help identify If you have IBD by testing for markers indicating the antibodies related to the disease. It helps determine if you have the condition and which type, and how severe it is.

Ferritin and Transferrin Tests

Ferritin is a protein that this test measures, which may tell if you have inflammation. Low levels of ferritin can mean low levels of iron, which means anemia. People with IBD usually suffer from anemia as well. Similarly, low levels of transferrin, a protein that binds iron, can mean iron deficiency.

Liver Function Tests (LFT)

A liver function test can indicate if you have inflammation, depending on the results. It may also show if you have rare liver complications due to IBD. This works with LFT measuring the levels of serum albumin and enzymes. If they’re low, you probably have inflammation.

Inflammatory Marker Tests

The proteins in the blood called biomarkers can be a sign of inflammation, which is a symptom of IBD. TPMT tests this, but it cannot diagnose IBD. However, this test can indicate that a person may have IBD.

Thiopurine S-Methyltransferase Test (TPMT)

TPMT can help see if you are at risk of having side effects due to thiopurine drugs used to treat IBD. If, after the test, you do not have detectable TMPT activity, then you may be at risk. However, this isn’t effective at identifying everyone with IBD.

Tests for Vitamins and Minerals

These are tests that determine which vitamins and minerals the body lack. They test for vitamins and minerals such as Vitamin B12 and folic acid, calcium and phosphate, magnesium, and trace minerals like zinc. All of these are affected when a person has Crohn’s disease. You can get a full snapshot of your nutritional health by getting a vitamin & nutrition blood test.


A blood test can detect Crohn’s disease but not fully diagnose it. It can only indicate if your body has inflammation and may have an IBD. With this information, your doctor can then proceed to do more tests. These other tests will make it clearer if the symptoms you’re having are due to inflammatory bowel disease. You can get a simple IBD profile blood test without a doctor’s note. The details are located here.

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