von Willebrand factor antigen and plasminogen activator inhibitor in giant cell arteritis.

Sixty three patients (51 women, 12 men) with giant cell arteritis were studied by serial analyses of von Willebrand factor antigen (vWF: Ag) concentration and plasminogen activator inhibitor activity. Their mean age at the time of diagnosis was 71 years. Two hundred and one randomly selected subjects from the general population, aged 75 years, served as controls. The mean concentration of vWF:Ag in the patients with giant cell arteritis before the start of corticosteroid treatment was 2.63 (SD 1.35) IU/ml compared with 1.71 (0.69) IU/ml in the general population. The vWF:Ag concentration slowly decreased and reached the control range about 18 months after the diagnosis. The vWF:Ag did not correlate with the clinical group of giant cell arteritis nor with the results of temporal artery biopsy. Flare ups and vascular complications were not indicated by the vWF:Ag. Plasminogen activator inhibitor activity in the patients was not significantly different from that of the general population at any time. It was concluded that the determination of vWF:Ag and plasminogen activator inhibitor activity is of limited clinical value in the diagnosis, prognosis, and monitoring of steroid treatment in patients with giant cell arteritis.