BACKGROUND: An Arg60-to-Leu mutation was found in the first cytoplasmic loop of the PLT TxA2 receptor as a new congenital PLT disorder characterized by impaired responsiveness to TxA2. However, it has not been clarified whether DDAVP is effective in correcting the bleeding time (BT) in this PLT disorder. STUDY DESIGN AND METHODS: DDAVP (0.4 microg/kg) was intravenously administered over 20 minutes in five patients with this PLT disorder, and template BT, PLT retention to glass beads, PLT aggregation, and a coagulation study were performed before and after the infusion of DDAVP. PLT TxA2 synthesis defects (cyclo-oxygenase deficiency, volunteers taking aspirin), thrombasthenia, and Bernard-Soulier syndrome were also included in this study. RESULTS: The normalization of BT was found in all patients with this PLT disorder, and one of the patients successfully underwent oral surgical procedures with DDAVP as the only hemostatic agent. DDAVP was also efficacious in the TxA2 synthesis defect but not in other disorders. FVIII coagulation activity, vWF antigen, and ristocetin cofactor significantly increased in all patients after DDAVP, but no changes were seen in the PLT retention rate and PLT aggregation study after DDAVP infusion. CONCLUSION: DDAVP was effective in correcting BT in patients with impaired responsiveness to TxA2 as well as impaired production of TxA2.
BACKGROUND: An Arg60-to-Leu mutation was found in the first cytoplasmic loop of the PLT TxA2 receptor as a new congenital PLT disorder characterized by impaired responsiveness to TxA2. However, it has not been clarified whether DDAVP is effective in correcting the bleeding time (BT) in this PLT disorder. STUDY DESIGN AND METHODS: DDAVP (0.4 microg/kg) was intravenously administered over 20 minutes in five patients with this PLT disorder, and template BT, PLT retention to glass beads, PLT aggregation, and a coagulation study were performed before and after the infusion of DDAVP. PLT TxA2 synthesis defects (cyclo-oxygenase deficiency, volunteers taking aspirin), thrombasthenia, and Bernard-Soulier syndrome were also included in this study. RESULTS: The normalization of BT was found in all patients with this PLT disorder, and one of the patients successfully underwent oral surgical procedures with DDAVP as the only hemostatic agent. DDAVP was also efficacious in the TxA2 synthesis defect but not in other disorders. FVIII coagulation activity, vWF antigen, and ristocetin cofactor significantly increased in all patients after DDAVP, but no changes were seen in the PLT retention rate and PLT aggregation study after DDAVP infusion. CONCLUSION: DDAVP was effective in correcting BT in patients with impaired responsiveness to TxA2 as well as impaired production of TxA2.