Circulating thrombopoietin in systemic sclerosis

Objective. To investigate circulating thrombopoietin (TPO) concentrations i n systemic sclerosis (SSc). Methods. TPO concentrations were measured by ELISA in serum samples of 13 p atients (11 female, 2 male) with diffuse SSc, 15 healthy controls (13 femal e, 2 male), and 15 patients (13 female, 2 male) with rheumatoid arthritis ( RA), Thrombocyte counts of patients with SSc and RA and controls were recor ded. Results. Median TPO concentrations were 115 (164) in SSc, 76 (32) in RA, an d 62 (34) pg/ml in controls. Median serum TPO concentration in the SSc grou p was significantly higher than other groups; there was no difference betwe en controls and patients with RA (p < 0.001 for both comparisons). Median p latelet counts of SSc, RA, and controls were 224 +/- 58 x 10(9)/1, 238 +/- 44 x 10(9)/l, and 272 +/- 35 x 10(9)/1, respectively. There was no correlat ion between thrombocyte counts and TPO levels in any group. Conclusion. We show that patients with SSc have higher serum TPO concentrat ions compared to healthy controls and patients with RA. It can be hypothesi zed that TPO mediated release of particular growth factors may participate in the pathogenesis of the fibrotic process of SSc.