Crohn's Disease causes inflammation of the bowel. The most commonly affected segments are the lower small intestine (ileum) and the large intestine (colon), but any part of the digestive tract may be involved, starting from the mouth all the way to the anus. The inflammation involves the entire thickness of the bowel wall. Such inflammation can cause abdominal pain, diarrhea and a number of other symptoms, including fever and weight loss.
The inflammation in Crohn's Disease used to be attributed to abnormalities in the function of the body's immune system. The immune system is made up of cells and special proteins that normally fight against infections and foreign bodies. In healthy individuals, the immune system does not produce a response against food, 'good' bacteria or other normal bowel components. In patients with Crohn's Disease, however, the immune system apparently overreacts to substances and bacteria in the intestine. White blood cells attack the inner lining of the intestines, resulting in the formation of inflammatory toxins which cause chronic tissue swelling, injury and ulceration.
The exact cause of this abnormal immune response is unknown. A genetic or inherited component to develop Crohn's Disease was also suggested. First-degree relatives (brother, sister, parent or child) of patients with Crohn's are more likely to develop the disease. Furthermore, certain chromosomal markers have been found in the DNA of patients with Crohn's Disease. Crohn's Disease is not caused by stress.
One of the common complications of Crohn’s disease is nutritional deficiencies, including deficiencies of certain proteins, calories and vitamins. These deficiencies, along with the direct effects of chronic inflammation, prolonged use of glucocorticoid as part of the treatment, poor nutrition, delayed puberty and low muscle mass are associated with poor skeletal health. Low bone mineral density is commonly reported. These factors render patients affected with Crohn’s Disease be more prone to develop fractures, and these fractures will require a longer time to heal.