Lab Testing and Inflammatory Bowel Disease

 Inflammatory bowel disease (or IBD) refers to several chronic disorders that are characterized by damaged and swollen tissues inside the digestive tract. The severity of those conditions will change over time and vary from one individual to the next. Periods of remission can alternate with times of active disease. During a flare-up, an individual might experience frequent bouts of bloody and/or watery diarrhea, fever, weight loss, and abdominal pain. Between flare-ups, the symptoms often diminish. Numerous individuals can go through extended remission periods in between their flare-ups.   

The Centers for Disease Control and Prevention reports that one to three million individuals in the United States are affected by irritable bowel syndrome. The cause of this disease is unknown, but there is some evidence pointing to a complex interaction of various factors that trigger an abnormal immune response, including microbes contained inside the digestive tract and a genetic predisposition for the disease.  

Ulcerative colitis (or UC) and Crohn disease (or CD) are the most common types of inflammatory bowel disease. Both sexes are subject to irritable bowel disease, although women more commonly have Crohn disease, and ulcerative colitis is more often found in men. Both are most commonly found in Caucasians as well as individuals living in developed countries who are of Ashkenazi Jewish origin. Nevertheless, in North America, irritable bowel disease is increasing among non-Caucasians as well.  

Either type of irritable bowel disease can affect people of all ages. Still, most cases are initially diagnosed in individuals 14-24 years old, along with a smaller set of cases that are diagnosed in people 50 to 70 years old. Along with having gastrointestinal symptoms, children who are affected by either ulcerative colitis or Crohn disease might suffer from growth retardation and delayed development. Individuals who are diagnosed with one of these conditions when they are young have an increased risk of developing colon cancer when they are older.  

Crohn Disease (CD) 

Any part of a person’s digestive tract can be affected by Crohn disease from the person’s mouth all the way down to their anus. However, it is mainly found in the colon (the bowel or large intestine) and/or in the final part of the individual’s small intestine (the ileum). Crohn disease can affect bowel tissues in patches, with healthy tissue in between patches.  

Fistulas or ulcers may be formed when inflammation penetrates deep inside of the tissues of the colon and intestines. Fistulas are tunnels in the intestines that make it possible for the body to move waste materials to other areas. Some other complications caused by Crohn disease can include infections, tears in anal skin, anemia that comes from bleeding tissues, and bowel obstructions. The Crohn’s & Colitis Foundation of America reports that around two-thirds to three-quarters of individuals who have Crohn disease will need surgery eventually, either to treat a fistula or obstruction or to remove damaged parts of the colon or intestines.  

Ulcerative Colitis (or UC) 

This condition mainly affects the colon’s surface lining. UC has symptoms that are similar to Crohn disease; however, the tissue inflammation from ulcerative colitis is continuous, not patchy like from Crohn disease. Usually, the inflammation begins at the anus and then proceeds up the colon. With ulcerative colitis, bloody diarrhea occurs more often than with CD. Toxic megacolon is the most serious type of complication caused by ulcerative colitis. This is a relatively rare acute condition where part of the colon basically becomes paralyzed. This paralyzation causes waste to stop moving through that part of the colon; the waste instead builds up and dilates the colon. That can cause weakness, fever, and abdominal pain. If left untreated, it may become life-threatening. Individuals who have toxic megacolon might need to have their large intestine removed surgically. 

Symptoms and Signs  

As the symptoms and signs of CD and UC intersect and are similar, it is hard to distinguish between them. Usually, symptoms develop gradually over a long period of time. However, at other times the symptoms might suddenly appear with no advance notice. While there can be periods of remission when symptoms and signs sometimes subside for several months or even years at a time, there are other times when the disease is quite active (flares), and the symptoms are the most obvious and noticeable.  

Although symptoms and signs can vary in severity and will be different from one individual to the next, the most common of them include the following:  

  • Unexplained weight loss and loss of appetite 
  • Bleeding from the rectum (leaves blood in the stool) 
  • Persistent diarrhea 
  • Pain and abdominal cramps  
  • Some less common symptoms and signs can include the following:  
  • Skin rashes 
  • Joint pain 
  • Anemia 
  • Fatigue 
  • Fever  
  • In youth and children, delayed growth and failure to thrive  

Tests for IBD 

Typically, a healthcare professional will collect information about a person’s family and medical history and the signs and symptoms the patient presents, before deciding on which tests to perform. The evaluation will likely look for extraordinary things that could be associated with things that cause diarrhea and other symptoms. 

Laboratory Tests 

 Inflammatory Bowel Disease cannot be diagnosed from the results of any one lab test. Nevertheless, testing is critical for individuals presenting as possible having  Inflammatory Bowel Disease. Persistent Diarrhea and pain in the abdomen suggest an initial set of tests. Imaging tests (like an X-ray or CT scan) may also be ordered. 

Common Initial Tests Include: 

C-reactive protein (or CRP) tests for inflammation and may be used to differentiate between IBD and irritable bowel syndrome (or IBS), and may also be to monitor the disease. 

Erythrocyte sedimentation rate (or ESR) may be used to detect inflammation where CRP testing is not available 

Fecal occult blood test or fecal immunochemical is used to find blood in the urine 

Complete blood count (or CBC) checks for anemia which is caused by IBD (and similar conditions) 

Comprehensive metabolic panel (or CMP) is used to evaluate general health 

Along with the initial tests and/or later, other tests may be performed to rule out other causes of abdominal pain, colitis, and diarrhea. These other potential causes include colon cancer, parasites, infections (either bacterial or viral), and other chronic conditions, including celiac disease.

Some of these tests are: 

  • Ova and parasite (or O&P) to find parasites 
  • GI pathogens panel or stool culture to detect digestive tract infection 
  • Cytomegalovirus to look for CMV infection 
  • Clostridium difficile tests to detect toxin produced by bacteria called C. Difficile.  C. Difficile may grow beyond healthy levels in the digestive tract 
  • Anti-tissue transglutaminase (or anti-tTG) and other CD tests 

There are many, many other tests which may be ordered depending on the circumstances: 

In the end, a biopsy may be conducted to establish a diagnosis of irritable bowel disease.