Thrombopoietin serum levels in patients with inflammatory bowel disease with and without previous thromboembolic events.

Background/aims: Patients affected by inflammatory bowel disease frequently suffer from thromboembolic complications and mesenteric microvascular occlusion could be involved in the pathogenesis of inflammatory bowel disease. Increased platelet counts and abnormal platelet function seem to play a crucial role in determining the hypercoagulable state observed in inflammatory bowel disease. Thrombopoietin is considered the primary regulator of thrombopoiesis and recent studies have investigated the role of thrombopoietin in inflammatory bowel disease. However, the available data are not conclusive. The aim of this study was to assess thrombopoietin serum levels in inflammatory bowel disease patients according to platelet counts, disease activity and previous thrombotic events.

Methodology: Seventy-one patients with inflammatory bowel disease [41 with ulcerative colitis and 30 with Crohn's disease] and 30 healthy controls were investigated. Eight (11%) inflammatory bowel disease patients had suffered previous thromboembolic complications, none had active thrombosis. Thrombopoietin serum levels were measured by ELISA.

Results: Mean thrombopoietin levels were significantly increased in inflammatory bowel disease patients with active disease compared to both healthy controls and patients with inactive disease. Platelet counts were significantly higher only in patients with active disease with respect to healthy subjects. No correlation was found between thrombopoietin levels and platelet counts in either controls or inflammatory bowel disease patients. No differences were found either in thrombopoietin levels or in platelet counts comparing inflammatory bowel disease patients with and without thromboembolic complications.

Conclusions: Our data show elevated thrombopoietin levels in active inflammatory bowel disease. However, no correlation was found between platelet counts and thrombopoietin levels, supporting the hypothesis that other circulating factors than thrombopoietin interact in determining reactive thrombocytosis. Furthermore, thrombopoietin levels did not differ in inflammatory bowel disease patients with or without previous thromboembolic events. This finding could be probably explained by the lack of patients with active thrombosis at the moment of inclusion in the study.