Behaviour of Von Willebrand Factor Antigen in Follow-up of Polymyalgia Rheumatica/Giant Cell Arteritis

Abstract
The von Willebrand Factor Antigen (vWF: Ag) is a high molecular weight glycoprotein synthesized by endothelial cells and megakaryocytes. It is present inside the endothelium cells in Welbel-Palade bodies (1) and is also present in the alpha granules of platelets (2). Elevated levels of vWF: Ag have been reported in several diseases characterized by vessel injury, such as scleroderma (3), glomerulonephritis (4), diabetes mellitus (5), Behcet's syndrome (6), Systemic Lupus Erythematosus, Rheumatoid Arthritis and vasculitis in general (7). Increased vWF: Ag plasma levels have also been described in patients with Giant Cell Arteritis (GCA) and/or Polymyalgia Rheumatic (PMR) (8, 9). In both these diseases an apparent or clinically hidden vasculitis is or may be present and vWF: Ag is reported to be most helpful in discriminating between PMR and GCA, since its levels seem to be higher in patients affected by GCA (8, 9).