Oxidative stress occurs as a result of increased activity of free radical-producing enzymes, decreased activity of free radical-removing enzymes, and insufficient levels of antioxidants. The most sensitive molecules to oxidation are lipids. Loss of cell membrane elasticity, increased cell fragility, and a shortened cellular life span results from oxidation of cell membrane lipids.

Free oxygen radicals may have an effect on the structural and functional damage of platelets and plays a role in pathogenesis of thrombocytopenia in both, acute and chronic ITP.

Selenium is an essential mineral found in small amounts in the body. It works as an antioxidant, especially when combined with other antioxidants as vitamin E , A and C. Antioxidants neutralize free radicals and may reduce or even help prevent some of the damage they cause.

aim of this study is to assess oxidant and antioxidant systems initially in patients with acute and chronic immune thrombocytopenia (ITP) and 6 months later.Another aim of the study is to evaluate effect of antioxidant therapy on bleeding score, platelet count and antioxidant status during 6 months follow-up.

Inclusion Criteria:

• 1. All patients less than 18 years with primary ITP; at initial presentation with platelet count less than 40 x 109/L attended Ain Shams Hematology clinic Children hospital from January 2013 and followed-up for 6 months.

  2. For acute ITP, patients will be newly diagnosed (about one month within the diagnosis).

  3. For chronic (12-24 months) and persistent (3-12 months) ITP patients.

Exclusion Criteria:

1. Patients' platelet count more than 40 x 109/L.; or above 18 years
2. Patients with secondary cause for thrombocytopenia.
3. Patients with any there associated chronic illness affecting oxidant status