TPO and Thrombocytopenia: In contrast to TPO which lowers the threshold for platelet activation, avatrombopag did not increase the number of circulating activated platelets as measured by platelet surface P-selectin and activated glycoprotein 2b/3a or the platelet reactivity to low or high concentrations of thrombin receptor-activating peptide and ADP in randomized, double-blind, placebo-controlled, parallel-group study of chronic liver disease patients with thrombocytopenia [54].