[L-asparaginase, antithrombin III deficiency and thromboses (author's transl)].

In 2 children treated for acute lymphoblastic leukemia (ALL), sural phlebitis followed treatment with L-asparaginase. The latter was responsible for a decreased synthesis of antithrombin III (AT III) resulting in low plasma activity. Treatment with heparin was not successful and only fresh plasma led to recovery. The activity of AT III, a progressive inhibitor of thrombin and cofactor of heparin, is always below 50% after L-asparaginase. However, since the risk of thrombosis is very low, interruption of treatment and fresh frozen plasma are needed only when additional risk factors are present.