Objectives: Elevated platelet count is a well recognized marker of inflammatory bowel disease (IBD) activity. Thrombopoietin (TPO) is a critical cytokine in the physiological regulation of thrombopoiesis. The aim of this study was to investigate the serum levels of endogenous TPO in patients with IBD, the relationship between platelet counts and TPO levels, and the correlation of TPO with the clinical characteristics of the patients.
Methods: TPO levels in 40 patients with Crohn's disease (CD), 63 patients with ulcerative colitis (UC), and in 42 healthy blood donors were assessed by ELISA. Platelet and white blood cell counts as well as C-reactive protein, and erythrocyte sedimentation rate were measured.
Results: TPO levels were significantly elevated in patients with CD (mean 124.3 +/- SD 58.0 pg/ml, p < 0.0001) and in patients with UC (mean 152.2 +/- SD 142.3 pg/ml, p < 0.0001), compared to controls (mean 53.4 +/- SD 45.7 pg/ml). TPO levels remained significantly elevated in remission (mean 144.7 +/- SD 131.1 pg/ml, p < 0.0001 compared to controls). Platelets were significantly elevated only in active CD, being normal in inactive disease as well as in all patients with UC. There was no significant correlation between TPO levels and various clinical characteristics of patients with IBD. No significant correlation was found between TPO levels and either platelet counts or white blood cell counts, erythrocyte sedimentation rate, and C-reactive protein.
Conclusions: TPO levels are increased in IBD, irrespective of disease activity, platelet counts, and clinical characteristics of the patients. These observations indicate that TPO, apart from being a platelet producer, might have additional functions, probably related to the procoagulant state of IBD.