Understanding Crohn’s Disease, Its Symptoms, Diagnosis, and Treatment

February 07, 2023 - The CDC estimates that roughly 3.1 million adults in the United States, accounting for approximately 1.3% of the population, have inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC).  This rate marks a significant rise in IBD, including CD, compared to previous decades. Despite falling under the same umbrella of IBD, CD and UC impact different parts of the gastrointestinal (GI) tract and have different symptoms and treatments. Even within CD, there are multiple different types. Considering the increasing prevalence of CD, it is critical that providers understand disease manifestations, diagnostic strategies, and treatment options.

Symptoms of CD, How It Differs from UC

While CD and UC are housed under the same umbrella of IBD, it is crucial to understand similarities and differences to deliver effective treatment. CD and UC are very similar diseases that may manifest with similar symptoms; however, there are slight differences between the two conditions. While CD can impact any part of the GI tract at any thickness, UC can only affect the inner lining of the large intestine.

According to the Crohn’s and Colitis Foundation (CCF), both conditions onset between 15 and 35 years or 55 and 70 years. The most common symptoms associated with CD are abdominal pain, diarrhea, weight loss, and fatigue. On the other hand, common symptoms of UC are stool urgency, fatigue, increased bowel movements, and abdominal pain. Additionally, bloody stools are common in UC while less common in CD. Conversely, malnutrition is not as common with UC as with CD.

Aside from the gastrointestinal symptoms associated with CD, it can also cause visual change, mouth sores, joint pain, dermatological complications, fever, appetite changes, night sweats, menstrual cycle changes, osteoporosis, and — in some severe cases — liver diseases such as cirrhosis.

Prevalence and Causes

CD is most common in North America, northern Europe, and New Zealand. Additional data on CD notes that it is most common in Caucasian populations, with an increasing incidence among Hispanic and Asian people. Data trends also show that CD is more common in urban communities, supporting the theory that environmental toxins can cause CD.

Little is understood about the etiology of CD. Some data suggest that immune responses to drugs, infections, toxins, and intestinal microbes can trigger the inflammation associated with CD. According to CCF, a normal immune response caused by bacteria, fungi, viruses, and other foreign microorganisms causes inflammation. However, the body typically does not have that response to common bacteria in the GI tract. In CD and other IBD, the body sees common gut bacteria as a threat and causes that inflammation consistently.

Other data suggest a genetic cause of CD, associated with mutations of the NOD2/CARD15. Having a first-degree relative with Crohn’s disease increases the probability of having CD by up to 28%, supporting the genetic link theory. However, there is some contention on the strength of this theory as some sources noted that genetic predisposition only increases CD risk by 1.5%.

“Even though there is a genetic component associated with increased risk of IBD, it is impossible to predict who may get Crohn’s disease based on family history,” CCF states on its website.

Types of CD

Multiple CD types are characterized by the different parts of the intestinal tract that are affected. One of the most common forms of CD is ileocolitis, which is associated with inflammation of the terminal ileum and the colon. According to CCF, ileocolitis is commonly associated with diarrhea, cramping, pain in the lower middle or right of the abdomen, and significant weight loss.

Ileitis is another type of CD that only impacts the ilium. Despite affecting less of the gastrointestinal tract, it can be characterized by the same symptoms as ileocolitis. Additional symptoms may include developing a fistula in the lower right of the abdomen.

Another type of Crohn’s — causing nausea, vomiting, appetite changes, and weight loss — is gastroduodenal CD. This type of CD impacts the stomach and the duodenum. Meanwhile, jejunoileitis is caused by inflammation of the jejunum, the upper half of the small intestine. This type of CD causes mild to intense abdominal pain and cramping, exacerbating after eating. Other symptoms include diarrhea and the development of fistulas in severe cases.

Crohn’s colitis — also known as granulomatous colitis — affects the colon, causing diarrhea, rectal bleeding, abscesses, fistulas, ulcers around the anus, skin lesions, and joint pains.

Diagnosing CD

A physical exam is usually the best place to start to determine whether a patient has Crohn's. If a patient is complaining of common symptoms of CD, the provider should continue to collect a history of overall health, nutrition, family history, and daily habits. Next, providers may consider ruling out other conditions associated with the patient’s symptoms through blood and stool test and X-rays.

If providers rule out other conditions, they may consider doing more involved imaging, such as endoscopy, biopsy, chromoendoscopy, and small intestine imaging. A lower endoscopy, also known as a colonoscopy, can allow providers to examine inflammation in the colon. Additionally, an upper endoscopy can enable providers to visualize the upper part of the GI tract to the duodenum.

A small tissue biopsy can be done with tissue collected during an endoscopy. The tissue can be screened for disease or other cancers. Chromoendoscopy is an endoscopy using blue dye to highlight changes in the intestinal lining to identify polyps and precancerous changes. Finally, small intestine imaging done through a digital pill can help providers visualize the entire GI tract.

Choosing the appropriate imaging option can depend on access, patient preference, and provider preference. Imaging may also be used during treatment to assess how effective a treatment is. A clinical trial in Denmark is currently evaluating the efficacy of some imaging tools in assessing CD treatments, comparing MRI, ultrasound, and capsule endoscopy.

CD Management

Crohn’s disease may be managed in multiple ways depending on the patient, the severity of the condition, and the patient’s lifestyle. Managing CD often involves a combination of treatments or medication.

Medication

One standard option for treating CD is medication. Multiple medications may mediate the immune response, manage and alleviate symptoms, and reduce inflammation.

According to the NIH, aminosalicylates, such as balsalazide, mesalamine, and sulfasalazine,  are commonly used to reduce inflammation in CD patients. However, typical side effects include diarrhea, headaches, heartburn, nausea, and abdominal pain. Despite the potential side effects, this medication may provide symptom relief that benefits the patient more than the possible side effects that can harm them.

Another medication option is corticosteroids, such as budesonide, prednisone, and methylprednisolone, which mediate immune responses and reduce inflation. These are not prescribed for long-term use as they may have severe side effects such as acne, bone mass loss, high glucose levels, high blood pressure, susceptibility to infection, mood swings, and weight gain. However, providers may consider these medications going through an excruciating period of CD.

Immunomodulators are also used in some cases but may cause low white blood cell counts, fatigue, pancreatitis, and GI disturbances. Finally, biologic therapies, such as adalimumab, natalizumab, and ustekinumab, that target specific parts of the immune systems may be recommended for patients who have not responded to other treatment options. On June 17, the FDA approved Skyrizi, an additional biologic to treat Crohn’s disease.

Nutrition

Another option for managing CD symptoms is to make lifestyle changes such as adjusting diet. Adequate nutrient intake is critical for those living with CD. Often CD causes a reduced appetite and worsens nutrient absorption due to diarrhea, which may cause secondary symptoms such as malnutrition and weight loss. Due to the GI disturbances caused by CD, many individuals also opt for soft, bland foods as they are easier to digest.

Understanding the role of nutrition in CD management requires additional research. Researchers from the University of Massachusetts School of Medicine are currently recruiting for a study to understand how dietary interventions may help in CD treatment. They are focusing on an interventional diet adapted from the Inflammatory Bowel Disease Anti-Inflammatory Diet.

Surgery

In many cases, patients may need surgery to alleviate symptoms and manage severe flare-ups. Up to 75% of people with CD may choose surgery as a treatment route. While not curative surgery can help resolve fistulas, fissures, obstructions, and more when medications can no longer treat these conditions. Surgical interventions require the resection of the diseased bowel and anastomosis of the remaining healthy tissue. Common surgeries include small bowel resections, subtotal colectomies, proctocolectomies, and ileostomies.