TPO and autoimmune thrombocytopenic purpura: Also, the hormone thrombopoietin (TPO), which is a GP produced in the liver and promotes thrombopoiesis, is unable to restore normal platelet counts. ITP can be categorized as primary, also called idiopathic, and secondary, which is caused by various illnesses like viruses, medications, autoimmune diseases, infections, and cancers [1].