Treatment of symptomatic patients with essential thrombocythemia: effectiveness of anagrelide.

We prospectively evaluated the effect of anagrelide (ANA) on platelets, PF4, F1+2, PAP, PAI-1, and TFPI and erythromelalgia in patients with essential thrombocythemia (ET) receiving anti-aggregants both pre- and post-ANA. At first, we observed a successful reduction of platelets, which was associated with normalization of platelet coagulant and endothelial function and disappearance of erythromelalgia. Secondly, we found a correlation between PF4 and TFPI and between TFPI and thrombosis, suggesting that erythromelalgia may be caused by platelet-mediated endothelial activation. These data may indicate that ANA may be efficacy in the treatment of symptomatic patients with ET.