Introduction: Epidemiological studies clearly indicate an increasing incidence of inflammatory bowel disease (IBD), especially in paediatric Crohn’s disease (CD), with decreasing age of the disease onset.

Aim: To define the characteristics of newly diagnosed, paediatric onset CD patients.

Material and methods: Demographic and clinical data of newly diagnosed CD patients under the age of 18, based on the prospective IBD patients registry and self-reported questionnaire, were compared.

Results: In the entire group of 146 CD patients, males predominated (56%) and were significantly younger at the time of diagnosis (11.25 ±4.48 years vs. 12.71 ±4.33 years, p = 0.04). No differences were found for either the mean age of onset of symptoms (9.98 ±4.69 years vs. 11.33 ±4.53 years, p = 0.08) or for the lag time between CD-related symptoms and establishing the diagnosis (13.65 ±21.66 months vs. 15.52 ±22.66 months, p = 0.79). Significantly more frequently girls presented with more active CD as assessed by PCDAI (66.63% vs. 40.74%, p = 0.028) with a significantly higher risk for growth impairment and higher odds for a lower haemoglobin level, hypoalbuminaemia, and increased ERS. The most frequent symptoms were abdominal pain, diarrhoea and rectal bleeding; however, this classic triad of symptoms occurred in only 37% of patients. Inflammatory behaviour (B1) and ileocaecal localization (L3) were found the most frequently and no gender differences were found according to initial disease classification.

Conclusions: These data revealed gender-related differences in paediatric onset CD; therefore genetic and/or hormonal factors could influence the disease clinical presentation at that age. Extensive disease location (L3) was expressed by most of the patients and inflammatory behaviour (B1) predominated. A high proportion of newly diagnosed paediatric CD patients presented with normal laboratory values which restricted their usefulness for the differential diagnosis.