The diagnosis of ITP is a process of exclusion.  First, it has to be determined that there are no blood abnormalities other than a low platelet count, and no physical signs other than bleeding.  Then, secondary causes (5–10 percent of suspected ITP cases) should be excluded.  Such secondary causes include leukemia, medications (e.g., quinine, heparin), lupus erythematosus, cirrhosis, HIV, hepatitis C, congenital causes, antiphospholipid syndrome, von Willebrand factor deficiency, onyalai and others.  All patients with presumed ITP should be tested for HIV and hepatitis C virus, as platelet counts may be corrected by treating the underlying disease. In approximately 2.7 to 5 percent of cases, autoimmune hemolytic anemia and ITP coexist, a condition referred to as Evans syndrome.