The investigators are trying to investigate the coagulation status of idiopathic (immune) thrombocytopenic purpura patients by measuring the platelet count, coagulation battery, von Willebrand factor level, thromboelastography.

In patients with chronic coagulation disorder, laboratory model and clinical data have shown evidence for a rebalanced hemostasis. Previous study showed that the platelet count may not predict the risk of bleeding since the platelet count is not an indicator of platelet function. Thromboelastography may be the choice of investigation when platelet function is in question especially in patients with idiopathic (immune) thrombocytopenic purpura (ITP). Previous study have shown that maximum clot formation is the most important thromboelastography parameter in predicting bleeding in ITP patients that makes thromboelastography superior to other hemostatic tests. The investigators are trying to evaluate the rebalanced hemostasis in patients with ITP by comparing the value of platelet count, von Willebrand factor antigen level, and thromboelastography parameters.

Inclusion Criteria:

• Those who visits the outpatients clinic of Samsung Medical Center with a diagnosis of idiopathic (immune) thrombocytopenic purpura (ITP)between March, 2012 and February, 2013.
• Those with age between 20 and 70 yrs old

Exclusion Criteria:

• Those with other causes of thrombocytopenia other than ITP

Those who visits the outpatients clinic of Samsung Medical Center with a diagnosis of idiopathic (immune) thrombocytopenic purpura between March, 2012 and February, 2013.