Primary immune thrombocytopenia (ITP) is an uncommon disease characterised by a low platelet count, which may cause the patient to have a higher risk or increased duration of bleeding. Individual hospitals only encounter a small number of ITP patients each year which makes it difficult to study this disease. By creating this disease registry, we will be able to build a more complete picture of ITP, including treatment practices, through collecting information about the condition from patients across several hospitals in several countries. Research of this kind will help future patients by providing doctors with information about ITP, and about how patients have been treated.