FACTOR-VIII-C INCREASES AFTER DESMOPRESSIN IN A SUBGROUP OF PATIENTS WITH AUTOSOMAL RECESSIVE SEVERE VON-WILLEBRAND DISEASE

Patients with severe von Willebrand disease (vWD) usually show no increase of factor VIII/von Willebrand factor (VIII/vWP) after desmopressin (DDAVP) infusion and the bleeding time (BT) remains markedly prolonged. We have tested the biological responsiveness to DDAVP in six patients, belonging to six different families, with phenotypic evidence for severe vWD. Baseline VIII:C ranged from 12 to 32IU/dl, ristocetin cofactor activity (RiCol) was unmeasurable in all the patients, vWF antigen (vWP:Ag) ranged from 0.5 to 3.5IU/dl, and in all patients the BT was longer than 30 min. No measurable vWf was present in patient's platelets, and plasma and platelet vWF multimers were virtually absent. An autosomal recessive pattern of inheritance was evident in all the propositi. After DDAVP infusion, there was no BT shortening. In four patients, VIII:C increased post-infusion and in three patients levels greater than 50 IU/dl were attained. RiCof reached a maximum of 11 IU/dl and vWF:Ag 9 IU/dL. In one of these four patients, DDAVP allowed a safe dental extraction, without resorting to blood products. In the remaining two patients no VII/vWF changes were observed after DDAVP. In conclusion, a subgroup of patients with severe vWD shows an increase of VII:C after DDAVP. A test infusion with this agent is advisable in patients with severe vWD before considering treatment with VIII/vWP concentrates.