Chronic inflammatory bowel disease, deep-venous thrombosis and antithrombin activity.

Of 34 patients with chronic inflammatory bowel disease (CIBD), 4 developed well-documented episodes of deep-venous thrombosis. All 4 patients had active disease at the time of thrombosis. This group was studied to determine if the tendency to deep-venous thrombosis in patients with CIBD was associated with reduced antithrombin activity by measuring the concentration of three thrombin inhibitors, antithrombin III (AT III), alpha 2-macroglobulin (alpha 2 M) and alpha 1-antitrypsin. 2 patients had low AT III levels and 10 had low alpha 2 M levels. 2 patients who developed deep-venous thrombosis had significantly low levels of both AT III and alpha 2 M. It is suggested that in patients with diseases predisposing to thrombosis and associated with low AT III levels, the measurement of alpha 2 M in addition to AT III may predict those particularly at risk.