Okay, so far we have covered what it is and that are the signs and symptoms. If you did not catch that entry you can check it out here. Now we will cover Causes along with Screening and Diagnosis.
Causes
The cause of Crohn’s disease is unknown. Several theories exist about what causes Crohn’s disease, but none have been proven. Some scientists suspect that infection by certain bacteria, such as strains of mycobacterium, may be the cause of Crohn’s disease. To date, however, there has been no convincing evidence that the disease is caused by infection. Crohn’s disease is not contagious. Although diet may affect the symptoms in patients with Crohn’s disease, it is unlikely that diet is responsible for the disease.
The human immune system is made from cells and different proteins that protect people from infection. The most popular theory is that the body’s immune system reacts abnormally in people with Crohn’s disease, mistaking bacteria, foods, and other substances for being foreign. The immune system’s response is to attack these “invaders.” During this process, white blood cells accumulate in the lining of the intestines, producing chronic inflammation, which leads to ulcerations and bowel injury.
Activation of the immune system in the intestines appears to be important in IBD. The immune system is composed of immune cells and the proteins that these immune cells produce. Normally, these cells and proteins defend the body against harmful bacteria, viruses, fungi, and other foreign invaders. Activation of the immune system causes inflammation within the tissues where the activation occurs. (Inflammation is an important mechanism of defense used by the immune system.)
Normally, the immune system is activated only when the body is exposed to harmful invaders. In patients with IBD, however, the immune system is abnormally and chronically activated in the absence of any known invader. The continued abnormal activation of the immune system results in chronic inflammation and ulceration. The susceptibility to abnormal activation of the immune system is genetically inherited. Thus, first degree relatives (brothers, sisters, children, and parents) of patients with IBD are more likely to develop these diseases. Recently a gene called NOD2 has been identified as being associated with Crohn’s disease. This gene is important in determining how the body responds to some bacterial products. Individuals with mutations in this gene are more susceptible to developing Crohn’s disease.
Scientists do not know if the abnormality in the functioning of the immune system in people with Crohn’s disease is a cause, or a result, of the disease. Research shows that the inflammation seen in the GI tract of people with Crohn’s disease involves several factors: the genes the patient has inherited, the immune system itself, and the environment. Foreign substances, also referred to as antigens, are found in the environment. One possible cause for inflammation may be the body’s reaction to these antigens, or that the antigens themselves are the cause for the inflammation. Some scientists think that a protein produced by the immune system, called anti-tumor necrosis factor (TNF), may be a possible cause for the inflammation associated with Crohn’s disease.
Diagnosis
The diagnosis of Crohn’s disease is based on a combination of exams: endoscopic, X-rays and histologic blood and tissue tests. Upon diagnosis, patients may need additional tests to monitor the disease and diagnose possible complications or side effects of medications.
Laboratory Tests
CBC (complete blood count) tests detect high white blood cell counts, which could indicate intestinal inflammation or infection and low blood counts (anemia) which might reveal intestinal bleeding. The presence of C-reactive protein can also indicate intestinal inflammation. Tests also monitor for side effects of certain medications. Liver function tests help screen for liver and bile duct abnormalities. Stool studies determine whether patients have treatable bacterial infections. Antibody tests can help clarify the situation for “indeterminate colitis” patients without a definite diagnosis.
Endoscopy – Several types of endoscopes are used to determine if the patient has ulcerative colitis or Crohn’s disease and how much bowel is affected. All use a thin, flexible tube with a lighted camera inside the tip, which allows doctors to look at the lining of the gastrointestinal (GI) tract. The image is magnified and appears on a television screen. Each procedure is named according to the section of GI tract examined:
- Sigmoidoscopy — Examines the lining of the lower third of the large intestine (the sigmoid colon).
- Colonoscopy — Examines the lining of the entire large intestine (colon), and sometimes can peek into the very end of the small intestine (or ileum).
- ERCP (Endoscopic retrograde cholangiopancreatography) — Examines the bile ducts in the liver and the pancreatic duct.
- Endoscopic ultrasound — Uses an ultrasound probe attached to an endoscope to obtain deep images of the gut below the surface. Used to diagnose perianal fistulas in patients with Crohn’s disease.
- Capsule endoscopy — Patients swallow a vitamin-sized capsule with a camera inside to produce images of sections of the small intestine that are beyond the reach of an EGD.
Radiology Tests – These radiologic tests provide information that endoscopy alone cannot:
- Plain X-rays
- Plain X-rays without contrast detect blockage in the large intestine.
- X-rays with Contrast – Contrast X-rays are used with endoscopy in monitoring and treating Crohn’s. These X-rays track special liquid contrast, usually barium, as it passes through the intestine, highlighting specific conditions.
- CT Scan -A CT scan takes simultaneous X-rays from different angles to reconstruct images of the internal organs.
- White Blood Cell Scan -Inflammation of the GI tract is characteristic of Crohn’s disease. Leukocyte scintigraphy (tagged white blood cell scan) detects white blood cell accumulation in inflamed tissue.
Stay tuned for yet more info soon…
* Complications
* Treatments
* Diet and taking care of your self
* Alternative Medicine
* Resources
