Inclusion Criteria:  Primary or secondary Immune Thrombocytopenia (ITP) Age ≥18 years signed declaration of consent  Exclusion Criteria:  diagnoses that cannot be reconciled with the diagnosis of ITP (esp. heparin-induced thrombocytopenia, pregnancy-associated thrombocytopenia, pseudothrombocytopenia) no informed consent possible (this covers patients who are unable to understand the nature and scope of participation)