Our results indicate that GC and E. coli L-asparaginase, in particular, induce hemostatic alterations which have implications on our understanding of thrombotic and hemorrhagic events during the treatment of ALL in children.

A multi-center retrospective survey was conducted to evaluate the incidence and types of hemostatic complications occurring in children with acute lymphoblastic leukemia (ALL) during treatment according to the ALL-BFM-90 treatment protocol. All of the BFM-treatment centers (n = 77) were approached and a 95% response rate with information on 1100 patients was obtained. Thrombotic or bleeding episodes occurred in 31 patients (2.8%), 19 of whom had thrombosis and 12 bleeding complications, involving the central nervous system (42%), the subclavian vein (29%), the gastro-intestinal tract, skin, lower extremities or pelvis (29%). Recovery was noted in 28 of 31 patients, while 3 died as a result of hemostatic complications. Bleeding or thrombosis occurred in patients receiving prophylactic substitution with plasma or plasma-derived concentrates (n = 16) as well as in those without substitution (n = 13). The majority of hemostatic complications (90%) occurred during the induction therapy of the treatment protocol, in particular during the period which included simultaneous administration of glucocorticoids and E. coli L-asparaginase. The concurrent administration of E. coli L-asparaginase and glucocorticoids may be an additional risk factor for thromboembolic events during therapy according to the ALL-BFM-90 protocol.

von Willebrand factor (vWF) antigen (vWF:Ag) and vWF-collagen binding activity (vWF:CBA) were measured in plasma by parallel quantitative ELISAs in normal newborns and infants (n = 71). The medians for vWF:Ag (IU/ml) and vWF:CBA (U/ml), respectively, were 1.46 and 1.91 for 2-7 day-old (n = 43), 1.22 and 1.40 for 2-4 week-old (n = 14), 1.22 and 1.15 for 2-6-month-old (n = 14) infants and 0.98 and 1.08 (n = 36) in normal adults. Elevated levels of vWF:Ag, but particularly vWF:CBA were seen for up to 4 weeks of life reaching adult levels between 2 and 6 months of life. The elevated levels of the vWF parameters indicate that caution should be exercised when interpreting laboratory data and diagnosing von Willebrand disease in newborns and young infants and warrant the use of age-specific reference ranges. The efficient haemostasis observed during early neonatal life may in part be due to the increased ability of vWF to interact with collagen.

Besides already known alterations of a variety of procoagulatory parameters, a relevant influence of VPA on the anticoagulatory system is demonstrated. We hypothesize that this additional alteration of anticoagulatory parameters might reduce the absolute bleeding risk of children treated with VPA.

Summary. We tested the response to desmopressin (1-deamino-cys-8-d-arginine-vasopressin; DDAVP) in four patients with haemophilia B [factor IX (F IX) at diagnosis 1´4±5%]. The activated partial thromboplastin time (aPTT) was significantly shortened in all patients. Although there was an up to 1´4-fold increase in F IX levels in three patients, maximal F IX activity remained below 10%. Much more prominent were the increases in F VIII (three-to fourfold), in von Willebrand factor antigen (VWF:Ag; 2´5-fold) and particularly in VWF collagen-binding activity (VWF:CBA; fivefold). These changes were reflected by the prophylactic efficacy of DDAVP for dental surgery. After pretesting, DDAVP could be a useful drug for reducing the need for plasma products for prevention of minor surgical bleeding in patients with mild to moderate haemophilia B.