GSTM1 and Thromboembolism: Other study indicated that the thromboembolism risk was associated with Hb levels ≤6 g/dL at onset, intravascular hemolysis, and previous splenectomy.[11] The risk of thromboembolism increases up to 15% in the acute phase of AIHA.[7,12] Thus, prophylactic anticoagulation therapy would be reasonable for patients with marked hemolysis.