Clotting abnormalities in children during maintenance chemotherapy for acute lymphoblastic leukemia.

BACKGROUND: Many of the drugs used in the treatment of acute lymphoblastic leukemia in children may induce modifications in different organs and functions. Following the observation of a recurrent, mild delay in the prothrombin time in ALL children during maintenance chemotherapy, we explored the main parameters of the clotting function. METHODS: 17 children with acute lymphoblastic leukemia were studied during maintenance chemotherapy for clotting function screening evaluation; 15 healthy children, matched for age and sex, were used as controls. RESULTS: A uniform pattern of slight prolongation of the prothrombin time with significantly reduced levels of factors VII, IX, and a trend toward reduced activity of factor X was observed in the absence of any demonstrable anticoagulant factor. CONCLUSIONS: Antileukemic maintenance chemotherapy is associated with a subclinical modification of the clotting parameters that is not responsible for hemorrhagic diathesis. Long-term administration of anti-metabolites (6-mercaptopurine and methotrexate) could be responsible for this reversible impairment.