DESMOPRESSIN-INDUCED THROMBOCYTOPENIA IN TYPE-I PLATELET DISCORDANT VONWILLEBRAND DISEASE

Thrombocytopenia after desmopressin (DDAVP) infusion is usually observ ed in patients with type IIB von Willebrand disease (vWD). No other su btypes of vWD with thrombocytopenia after DDAVP have been reported so far. We describe here the occurrence of thrombocytopenia after DDAVP i n a 39 year old male and his son with phenotypic characteristics of ty pe I vWD, ''platelet discordant subtype.'' After DDAVP, the abnormal r istocetin cofactor/von Willebrand factor antigen ratio in plasma was n ot corrected and the bleeding time remained markedly prolonged. Platel et count dropped 30 min after DDAVP (from 279 to 96 x 10(3)/muL in the propositus and from 298 to 116 x 10(3)/muL in his affected son) and r eturned to normal at 60 min. Platelet clumping was evident on peripher al blood smears obtained after infusion. These cases indicate that aft er DDAVP thrombocytopenia can occur in vWD other than type IIB.