Serum thrombopoietin levels in relation to disease status in patients with immune thrombocytopenic purpura.

Pre- and post-treatment serum thrombopoietin (TPO) concentration was measured in 35 patients with immune thrombocytopenic purpura (ITP). Mean post-treatment levels were significantly lower (P = 0.02) than pretreatment and not different for treatment modality. No significant correlation between pre- or post-treatment TPO and platelet counts was demonstrable (R = -0.325, P = 0.056 and R = -0.227, P = 0.190 respectively). In patients with very low platelet counts (< or =20 x 10(9)/l), pretreatment serum TPO was significantly higher than in patients with higher counts (P = 0.033). The logarithm of the platelet turnover rate, measured in 15 patients, correlated with pretreatment TPO levels (R = 0.64). These findings suggest a contributory role for TPO in the mechanism of ITP.