Crohn's disease is one of the two Chronic Inflammatory Bowel Diseases, internationally referred to as Inflammatory Bowel Disease (IBD). Crohn's disease can affect any part of the digestive system, from the mouth to the anus. Most commonly, it affects the end part of the small intestine (terminal ileum) or the colon.

Crohn's disease is often associated with systemic autoimmune disorders such as rheumatic arthritis. The causes of the onset of Crohn's disease are still unknown, although it has been shown that an inadequate and continuous activation of the immune system of the intestinal mucosa may cause the typical disorders associated to this disease. Today we know that the onset of Crohn's disease can be related to three factors that interact with each other: the genetic predisposition to the disease; the deterioration of tissues due to an immune reaction triggered by bacteria of the gastrointestinal tract flora; various environmental factors including cigarette smoking, which increases the risk of the onset of this disease.


Crohn's disease can occur at any age. However, the highest incidence occurs between the ages of 15 and 35 and over 65, although cases found in children are not uncommon. Today there is no National Register and data are not very reliable. Based on a research carried out by A.M.I.C.I. (Associazione Nazionale per le Malattie Infiammatorie Croniche Intestinali, The Italian National Association for Chronic Inflammatory Bowel Diseases), it is estimated that in Italy there are at least 100.000 people suffering from intestinal inflammatory diseases, of which probably 30-40% affected by Crohn's disease. Crohn's disease appears to be more common in Western countries and is rare, if not absent, in Third World countries. The number of new cases per year by number of inhabitants (incidence) of Crohn's disease seems to be increasing even if this, in part, may be due to a greater accuracy in the formulation of the diagnosis by doctors.


The symptoms of Crohn's disease can initially be misleading: at first only a feverish state can appear, but later abdominal pains occur especially in the lower right quadrant of the abdomen (right iliac fossa), an area where the disease locates more often. Pain arises spontaneously, is dull, continuous and is accentuated on palpation. Here the perception of irregular and painful swollen masses is frequent. Crohn's disease is also characterized by the presence of diarrhea (3-4 discharges a day), with semi-liquid or aqueous stools, with no visible blood (although episodes of occult bleeding are frequent).

The inflammatory process caused by Crohn's disease, especially if it involves large tracts of intestine, alters the absorption mechanisms of different substances due to the lack of reabsorption of the bile salts, which normally stimulate the reabsorption of food fats and, therefore, can also determine the appearance of steatorrhea (fats in the stool).


Crohn's disease can give rise to extraintestinal complications that can affect the articular, renal, ocular, hepatic and cutaneous apparatus. The variability of symptoms at the onset of Crohn's disease and the frequent presence of extraintestinal complications (i.e., one-limb nodular erythema or ocular problems) require close integration between different clinical specialties, as the diagnosis may be difficult and certainly slower. In recent years, however, diagnostic techniques have improved greatly and the period between the appearance of symptoms and clinical signs and the definitive diagnosis has significantly reduced compared to the past. As in many other diseases, the final diagnosis, as well as the patient's clinical history and symptoms, also draws a valid support from laboratory data.

People with Crohn's disease normally have higher calprotectin values​ than healthy subjects. The use of calprotectin as a non-invasive marker to detect the presence of an intestinal inflammation is not limited to the laboratory diagnosis phase of IBD, but is also used in the follow-up and monitoring of the specific therapy. Calprotectin is therefore a very useful support for the differential diagnosis between organic and functional disease.


Crohn's disease is a chronic disease and, therefore, there is never a complete cure. Generally, more or less protracted periods of remission alternate with phases of exacerbation. The prognosis of Crohn's disease is less favourable than that of ulcerative colitis. In general, mortality increases with the duration of the disease and affects about 5-10% of patients: the most frequent causes of death are peritonitis and generalized infections.