Increased antithrombin III concentration in children with acute lymphatic leukaemia receiving L-asparaginase therapy.

Previous reports have observed a fall in antithrombin III (AT III) concentration in patients receiving L-asparaginase as part of acute lymphatic leukaemia (ALL) induction therapy. The aim of this study was to define any qualitative changes in AT III that might arise during the course of L-asparaginase therapy and predispose to coagulopathy. Serial AT III profiles were studied in 12 patients with ALL receiving a course of L-asparaginase for 21 consecutive days as part of induction therapy. AT III isoforms were examined by isoelectric focusing in polyacrylamide gels (IEF/PA) and immunoblotting, and no changes were observed throughout the study period. Contrary to expectation, AT III antigen was significantly increased on treatment, while AT III activity remained unchanged. Fibrinogen levels, in contrast, fell considerably by 1 week of therapy and had not reverted to pre-treatment values 1 week after completion of asparaginase. No coagulation or bleeding disorders were observed during or after the study period.