73978-9

LOINC code 73978-9 identifies "von Willebrand factor (vWf).activity [Units/volume] in Platelet poor plasma by Immunoassay". Von Willebrand Factor Activity (VWF Activity, vWF:Act) in plasma specimens can be quantitatively determined by immunological methods. This code is created for, but not limited in use to, the submitter's kit, HemosIL Von Willebrand Factor Activity Kit, which determines VWF activity by measuring the increase of turbidity produced by the agglutination of the latex reagent. This assay uses a specific anti-VWF monoclonal antibody directed against the platelet binding site of VWF, glycoprotein Ib receptor, and reacts with the VWF in patient plasma. The degree of agglutination is directly proportional to the activity of VWF in the sample and is determined by measuring the decrease of transmitted light caused by the aggregates. The submitter's lab reports the results in U/mL where U represents "units" rather than the standard meaning of U, which is mmol/Min, a measure of enzyme rates. Additional testing (e.g. ristocetin cofactor assay) may be needed to confirm a diagnosis of von Willebrand disease (VWD).

This code measures von Willebrand factor.activity in PPP. It belongs to the COAG class in the LOINC classification.

LOINC (Logical Observation Identifiers Names and Codes) is a universal standard for identifying laboratory and clinical observations. It is maintained by the Regenstrief Institute and used worldwide for health data exchange.