[Utility of desmopressin in 4 cases of thrombocytopathies associated with giant platelets].

Shear-induced aggregation requires the platelet glycoprotein complexes (Gp), the von Willebrand factor (vWf) and ADP. The Bernard Soulier syndrome (BS) and the gray platelet syndrome (GPS) are platelet function defects characterized by absence of GP Ib/IX and alpha granules, respectively, with mucocutaneous hemorrhages, prolonged bleeding time (BT) and moderate thrombocytopenia in both syndromes. There are reports that desmopressin (DDAVP) shortens the BT in some patients with platelet dysfunction. The purpose of this study was to evaluate the response t(DDAVP) in four female patients (2 with GPS plus Marfan's disease and 2 BS). All had bleeding episodes, BTs > 10 minutes, platelet counts (PC) between 40-88 x 10(9)/L and defects in platelet aggregation. The DDAVP was administered at a dose of 0.3 microgram/kg in 15 to 30 mL of isotonic saline given by slow intravenous drip in 30 to 45 min. All patients were studied before and after DDAVP administration (BT, PC, platelet factor, mean platelet volume, factors F.VIII:C, FvW:Ag, FvW:RiC of, and platelet aggregation). After DDAVP infusion the patients had a BT < 6 min, and increased levels of F. VIII:C, FvW:Ag and FvW:RiC of (> 100 Ul/dL), and the bleeding disappeared. We conclude that there was a good response to DDAVP probably associated with improved platelet adhesion, and increases in the multimers of the von Willebrand factor.