Crohn's disease commonly affects the terminal ileum and colon but may be seen anywhere from the mouth to anus. It involves inflammation of the walls of the GI tract, associated with periods of remission and exacerbation.

Epidemiology:

• most diagnosis occurs between the ages of 20-29.
• There is a second incidence peak in the 7th decade.
• Crohn’s is also known to affect young children.

Cause:

The disease is probably brought on by a combination of 3 factors –

• genetic susceptibility
• environmental factors (smoking, oral contraceptive pill, high sugar diet, nutritional deficiencies - zinc, infectious agents - measles)
• the patient’s own immune response.

Types

Generally, Crohn’s can be divided into 3 types:

• Colonic (25%)
• Ileocaecal (40%)
• Small intestine alone (30%)

The duodenum is affected in about 2% of cases, and the stomach even more rarely. Where the stomach and duodenum is affected, there may be symptoms of B12 and iron deficiencies.

In lots of cases of Crohn’s there is malabsorption of various things due to structuring and fibrosis (leading to shortening) of the small intestine.

Distinctive features