An Epidemiological Study of Subjects With Immune Thrombocytopenic Purpura to Evaluate the Relationship Between Platelet Counts, Endogenous Thrombopoietin Levels, Endogenous Anti-Thrombopoietin Antibodies, and Selected Autoimmune Markers

Diagnosis of ITP, based on the history, physical examination, complete blood count, and examination of the peripheral smear, which should exclude other causes of thrombocytopenia. These criteria for ITP are based on the American Society of Hematology practice guideline for ITP. Subjects 5 years of age or older. Before the study specific procedure, the subject or legally acceptable representative must give written informed consent(s) for participation in the study. No subjects with documented history of Human Immunodeficiency Virus (HIV) or Hepatitis. No subjects with known underlying causes of thrombocytopenia such as lupus erythematosus, autoimmune thyroid disorders, drug-induced thrombocytopenia, bone marrow disorders, and liver disease. No psychiatric or addictive disorders that compromise the subject's ability to give truly informed consent for participation in the study.