Elevated thrombopoietin serum levels in patients with inflammatory bowel disease

OBJECTIVES: Elevated platelet count is a well recognized marker of inflamma tory bowel disease (IBD) activity. Thrombopoietin (TPO) is a critical cytok ine in the physiological regulation of thrombopoiesis. The aim of this stud y was to investigate the serum levels of endogenous TPO in patients with IB D, the relationship between platelet counts and TPO levels, and the correla tion of TPO with the clinical characteristics of the patients. METHODS: TPO levels in 40 patients with Crohn's disease (CD), 63 patients w ith ulcerative colitis (UC), and in 42 healthy blood donors were assessed b y 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 1 24.3 +/- 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 p g/ml). TPO levels remained significantly elevated in remission (mean 144.7 +/- SD 131.1 pg/ml, p < 0.0001 compared to controls). Platelets were signif icantly elevated only in active CD, being normal in inactive disease as wel l as in all patients with UC. There was no significant correlation between TPO levels and various clinical characteristics of patients with IBD. No si gnificant correlation was found between TPO levels and either platelet coun ts or white blood cell counts, erythrocyte sedimentation rate, and C-reacti ve protein. CONCLUSIONS: TPO levels are increased in IBD, irrespective of disease activ ity, platelet counts, and clinical characteristics of the patients. These o bservations indicate that TPO, apart from being a platelet producer, might have additional functions, probably related to the procoagulant state of IB D. (C) 2000 by Am. Cell. of Gastroenterology.