Crohn's Disease Symptoms & Diagnosis - HanStep Korean Medicine Clinic

Crohn's Disease

Symptoms & Diagnosis of Crohn's Disease

An accurate diagnosis is the first step toward proper treatment.

Definition & Statistics

A Chronic Inflammatory Bowel Disease
Affecting All Layers of the Digestive Tract

Crohn's disease is an autoimmune condition and, along with ulcerative colitis, is a type of Inflammatory Bowel Disease (IBD). It is an inflammatory condition that can cause inflammation throughout the entire digestive tract, from the mouth to the anus, and across all layers of the tissue. Inflammation mainly occurs in areas such as the duodenum, small intestine, and large intestine, and clinical symptoms vary depending on the site of inflammation.

Unlike ulcerative colitis, where inflammation is limited to the mucosal and submucosal layers, in Crohn's disease, inflammation can affect all layers of the intestinal wall, potentially leading to edema, strictures, obstructions, perforations, fistulas, and anal fissures. The inflammation occurs discontinuously and can cause symptoms outside the gastrointestinal tract, such as in the skin and joints.

About 20-30% of cases occur in childhood or adolescence, with the highest incidence between 15 and 35 years of age. Onset during childhood or adolescence can result in stunted growth. Furthermore, Crohn's disease is characterized by poor healing of wounds and surgical sites in cases involving fistulas or anal fissures.

Crohn's Disease Surgery Statistics

* 80% experience bowel resection within 20 years of diagnosis
* 20~40% of patients undergo their first surgery within 3 years
* 28% of surgical patients require re-surgery within 5 years, with 68% of those requiring surgery within 2 years

Etiology

Causes Involving Complex Interactions of Various Factors

It is known that various factors such as genetic, immunological, and environmental factors work in combination.

GENETICS

Genetic Predisposition

Genetic mutations such as IL23R and
influence of family history

IMMUNITY

Immune Dysregulation

Overactivated immune responses (Th1/Th17),
increased inflammatory cytokines (TNF-α, IL-12/23, etc.)

MICROBIOME

Gut Microbiome Changes

Gut microbiome imbalance and
reduction in beneficial gut bacteria

ENVIRONMENT

Environmental Factors

Smoking, diet, stress,
exposure to antibiotics, etc.

Symptoms

Main Symptoms

Different symptoms and examinations are required depending on the location of inflammation.

Gastrointestinal Symptoms

Chronic diarrhea, abdominal pain, weight loss, and bloating occur.

Abdominal pain and vomiting due to intestinal strictures or obstructions may appear. In cases of chronic inflammation in the intestinal wall, fibrosis may progress, leading to narrowing (stricture) or blockage (obstruction). In modern Western medicine, it is understood that strictures or obstructions caused by advanced fibrosis are irreversible and do not recover.

Perianal Lesions

- Perianal fistulas (fistula)
- Anal abscess
- Perianal fissures (fissure)

Systemic Symptoms

- Fatigue
- Fever
- Loss of appetite
- Growth retardation/reduction

Extraintestinal Symptoms

- Arthritis
- Dermatitis (erythema nodosum)
- Ocular inflammation (uveitis)
- Hepatobiliary disease

"Because Crohn's disease can cause inflammation across all areas and layers of the digestive tract,
a variety of diagnostic methods are required."

Diagnosis

Types of Diagnostic Tests

Compared to ulcerative colitis, Crohn's disease requires more diverse diagnostic methods to assess inflammation because it can affect all areas and layers of the digestive tract.

1. Clinical Symptoms

Checking for diarrhea, abdominal pain, weight loss, perianal lesions, etc.

2. Endoscopy

Colonoscopy: Used if inflammation in the large intestine is suspected.
Gastroscopy: Used if inflammation in the stomach or duodenum is suspected.
Capsule Endoscopy: Used if inflammation or bleeding in the small intestine is suspected.

* Identifies discontinuous inflammatory lesions, longitudinal ulcers, cobblestone appearance, and strictures/fistula openings. Endoscopy only allows visualization of inflammation on the inner lining of the intestines.

3. Stool Test

Includes a fecal calprotectin test (a measure of intestinal inflammation) and a fecal occult blood test. If inflammation is localized in the duodenum or small intestine, fecal calprotectin levels may show lower results.

4. Biopsy

Performed during endoscopy to examine changes in the mucosal tissue.

5. Blood Test

Checks for elevated inflammatory markers like CRP, ESR, and signs of anemia. However, blood tests often have low reliability, as inflammatory markers can remain normal even when intestinal inflammation is present.

6. Imaging Tests

CT, MRI, or contrast-enhanced studies are essential in cases of intestinal obstruction or strictures. For fistulas or abscesses, CT, MRI, and ultrasound are used for diagnosis and evaluation.

Risks and Limitations of Examinations

Risks of Endoscopy

1. Disruption of Gut Microbiome: Bowel preparation solutions taken before a colonoscopy have the effect of flushing out the normal gut microbiome, which can lead to its destruction. It may take several months for the microbiome to recover.

2. Risk of Intestinal Injury: Depending on the proficiency of the practitioner, the endoscope can scratch or bump the colon wall during insertion, causing injury or, in severe cases, perforation.

3. Capsule Endoscopy Limitations: The swallowed capsule may occasionally become stuck in the digestive tract.

Risks of Imaging Tests

Radiation Exposure: Repeated CT scans can lead to issues related to excessive radiation exposure.

Contrast Agent Toxicity: Contrast agents used to evaluate intestinal strictures can be nephrotoxic (toxic to the kidneys).

Key Diagnosis

Fecal Calprotectin Test
(FC)

A highly reliable biological marker
with over 80% correlation with colonoscopy

Fecal calprotectin is a biological marker secreted by neutrophils (a type of white blood cell) involved in intestinal inflammation. It is secreted when intestinal inflammation is present and not when it is absent. Since the amount secreted varies with the degree of inflammation, it is widely used in the diagnosis and monitoring of IBD.

Various studies show it is a reliable indicator with a sensitivity of 93% and a specificity of 96%. It has high reliability, with an agreement rate of over 80% with colonoscopy. (If the calprotectin level is poor, the colonoscopy result is generally poor, and if the calprotectin level is good, the colonoscopy result is generally good.)

* Note: If there is no inflammation in the large intestine but only in the duodenum or small intestine, or if there is inflammatory edema in the intestinal wall, the reliability or diagnostic value of calprotectin may decrease. Levels can also rise in cases of bacterial/viral enteritis, celiac disease, lymphoma, or food allergies, so differential diagnosis is necessary.

Reference Guide (mg/kg)

Normal 50.0 ~ 100.0 or less

Borderline 100.0 ≤ Value ≤ 200.0 ~ 250.0

* Essential to check for differential diagnosis

Inflammation 200.0 ~ 250.0 or higher

Limitations of Blood Inflammatory Markers

Blood inflammatory markers have low reliability. In actual clinical practice, inflammatory substances from the intestinal mucosal surface do not frequently penetrate the intestinal wall to enter the bloodstream; therefore, blood inflammatory markers often remain normal even when endoscopic inflammation is severe. However, in cases involving intestinal wall inflammation, fistulas, or anal fistulas, these markers can have a direct impact on the blood, leading to elevated CRP and ESR levels.

Levels rise in infectious diseases; since Crohn's disease and ulcerative colitis are not infectious, these levels are often normal. Long-term or high-dose use of immunosuppressants can cause white blood cell counts to drop, leading to decreased immunity. Levels may rise if there are anal fistulas or abscesses in Crohn's disease.

An acute-phase reactant produced and released into the bloodstream within hours after the onset of infection or inflammation. It can also rise due to heart attacks, sepsis, viral infections, or intense exercise. It allows for the assessment of the acute level of inflammation. Generally, the normal range is < 0.5 mg/dL, but unit variations may occur, so always verify reference ranges.

When blood is drawn and allowed to settle, red blood cells aggregate and separate from plasma. The rate at which this occurs changes based on the charge on the red blood cell surface, which is affected by inflammatory levels. This measured rate is the ESR. An average of < 20mm/h is normal; values vary by age and gender and reflect long-term inflammatory status.

Main Complications of Crohn's Disease

Intestinal stricture
Intestinal perforation
Intestinal-intestinal or intestinal-cutaneous fistula
Intra-abdominal abscess
Nutritional deficiency and growth failure due to malabsorption