Shortening of bleeding time by 1-deamino-8-arginine vasopressin (DDAVP) in the absence of platelet von Willebrand factor in Gray platelet syndrome.

The Gray platelet syndrome is a rare disorder characterised by the absence of platelet alpha-granules and their contents. We describe a new patient and the effects of infusions of 1-deamino-8-arginine vasopressin (DDAVP). The patient had a prolonged skin bleeding time and his platelets had reduced numbers of alpha-granules, increased vacuolation and reduced retention on glass beads. Platelet von Willebrand factor antigen (vWf:Ag) was undetectable and levels of platelet fibrinogen, beta-thromboglobulin, platelet factor 4 and thrombospondin were reduced. All tests of plasma coagulation factors were normal, including Factor VIII (F.VIII:C), vWf:Ag, ristocetin cofactor (R:CoF) and botrocetin cofactor. Platelet ATP, ADP, platelet albumin, surface membrane glycoproteins and 14C-serotonin uptake were also normal. Infusions of DDAVP increased plasma F.VIII:C, vWf:Ag and R:CoF and shortened the bleeding time on two occasions. This suggests that DDAVP shortens the bleeding time by releasing vWf:Ag and/or other proteins from cellular storage sites other than the platelet.