Free protein S deficiency in patients with chronic inflammatory bowel disease.

Free protein S, protein C, and C4b-binding protein (C4b-BP) were measured in randomly selected outpatients: 22 with Crohn's disease (CD) and 16 with ulcerative colitis (UC). Active disease was recorded in 10 patients with CD and 4 with UC. Fourteen patients (63.6%) with CD and 4 (25%) with UC had free protein S values below the normal range, with mean values of 62% and 78% of that found in healthy control subjects (p < 0.01). The C4b-BP level was 127% in patients with CD as compared with 89% in both healthy subjects and UC patients (p < 0.01). The protein C levels were similar in the three groups. The present results add to the factors already known favouring thromboembolic complications in inflammatory bowel disease and which might play a major role both for the pathogenesis and for the increased tendency to venous thromboembolism in these diseases.