CPT® Code 85246

The CPT® Code 85246 refers to a laboratory test specifically designed to measure the levels of factor VIII and von Willebrand (VW) factor antigen in the blood. Factor VIII, also known as antihemophilic factor, is a crucial protein involved in the blood coagulation process. It works in conjunction with von Willebrand factor, which serves as a carrier protein for factor VIII, thereby stabilizing its activity in promoting blood clotting. Von Willebrand factor exists in two distinct forms: one that circulates freely in the plasma and another that is bound to the alpha granules of circulating platelets. The synthesis and release of plasma von Willebrand factor occur in the vascular endothelial cells, while the platelet-bound form is produced by megakaryocytes in the bone marrow. The test for VW factor antigen quantifies the mass of this antigen present in the blood; however, it is important to note that it does not assess the functional activity of von Willebrand factor. Decreased levels of VW factor antigen can indicate potential inherited disorders, such as congenital von Willebrand disease, or may arise from acquired conditions including monoclonal gammopathies, lymphoproliferative disorders, autoimmune diseases, or hypothyroidism. Conversely, elevated levels of VW factor antigen can be associated with various conditions, including pregnancy, estrogen use, acute phase inflammation, physical exercise, stress, liver disease, vasculitis, and thrombocytopenic purpura hemolytic uremic syndrome. This test is often ordered as part of the initial evaluation for von Willebrand disease. To perform the test, a blood sample is collected through a separately reportable venipuncture, and the analysis is conducted on platelet-poor plasma using a microlatex particle-mediated immunoassay.