Fatal pulmonary embolism and antithrombin III deficiency in adult lymphoblastic leukaemia during L-asparaginase therapy.

We describe 2 adult patients with acute lymphoblastic leukaemia (ALL) who died from pulmonary embolism following L-asparaginase treatment. Since this drug is known to cause a decrease in antithrombin III, the most important protein physiologically involved in the neutralization of thrombin, we studied the behaviour of this inhibitor in 14 ALL patients treated with a protocol including a 14-day course of L-asparaginase. A significant but transient fall of biological and immunological antithrombin III and a concomitant reduction of fibrinogen were documented.