The incidence of thromboembolic disease is increased in patients with inflammatory bowel disease. Hyperhomocysteinemia is one of the risk factors for thrombosis.

The aims were: 1) to assess the prevalence of hyperhomocysteinemia in a large series of patients with Crohn's disease; 2) to search for clinical and biological factors associated with hyperhomocysteinemia.

One hundred seventy-one patients with Crohn's disease (64 males, 107 females), median age 31 years (range: 16-82), were studied. The median duration of the disease was 7 years. The concentrations of homocysteine, folate, cobalamin and C-reactive protein were measured in serum from blood sample of each patient.

The mean concentration of seric homocysteine was 14.8 µmol/L (N: 4.4-12.4 µmol/L). Hyperhomocysteinemia was observed in 89 patients (52 %). It was significantly associated with age, sex, smoking habit, serum cobalamin level and history of ileal surgical resection (P < 0.05). In the group of operated patients, there was a statistically significant association between hyperhomocysteinemia and the length of small bowel resected. In multivariate analysis, sex and smoking were associated with hyperhomocysteinemia.

More than half of the patients with Crohn's disease have hyperhomocysteinemia. This result stresses the need for preventing reversible factors associated with hyperhomocysteinemia, such as smoking and cobalamin deficiency, in order to lower the thrombotic risk of patients with Crohn's disease.