[Coagulation tests in von Willebrand's disease(author's transl)].

The diagnosis of von Willebrand's disease can be made by a selected series of easily performed clotting tests. A STudy of 36 patients with the disease (all but one with a mild form) revealed a significantly increased reaction time in the thrombelastogram from 210 plus or minus 33 percent to 270 plus or minus 69 percent (P less than 0.001), and of the partial thromboplastin time from 43 plus or minus 3s to 54 plus or minus 9s (P less than 0.001 than 0.001). Factor VIII activity was corresponding significantly reduced from normal (127 plus or minus 51 percent) to 51 plus or minus 12 percent (P less than 0.001). Other plasma factors and platelet counts were within normal limits. A platelet defect was indicated by an abnormal change in the speed of clot formation (k-time) from 162 plus or minus 39 percent to 341 plus or minus 121 percent (P less than 0.001), maximal thrombelasticity from 121 plus or minus 16 percent to 75 plus or minus 22 percent (P less than 0.001), and marked reduction in platelet-factor 3 liberation from 122 plus or minus 59 percent to 23 plus or minus 16 percent (P less than 0.001). An increase in bleeding time, from 162 plus or minus 41s to 204 plus or minus 128s (P less than 0.05), was not always present. Recently introduced immunological methods for determining factor VIII and factor VIII-associated protein, as well as special platelet-function tests, give further information on the pathogenesis of the bleeding disease, but their complexity restricts them to special laboratories.