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REAADS von Willebrand Factor Antigen Test Kit

CORGENIX MEDICAL CORPORATION · Model 034-001 · UDI-DI 00855360006038

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510(k) clearances

Adverse events

Recalls

Facilities

Description

INTENDED USE An enzyme-linked immunosorbent assay (ELISA) for the quantitative determination of Von Willebrand Factor Antigen (VWF: Ag) in citrated human plasma. For In Vitro Diagnostic Use. SUMMARY THE TEST Von Willebrand Factor Antigen (VWF:Ag or Factor VIII-related protein) is a plasma protein found in circulation combined by non-covalent interactions with Factor VIII (FVIII:C), a pro-coagulant protein also known as the anti-hemophilic factor. These two proteins show distinct biochemical and functional properties as well as different antigenic determinants; their plasma levels may vary independently of each other. Deficiency of FVIII causes classic hemophilia while deficiency of VWF causes Von Willebrand disease. VWF:Ag plays a very important role in hemostasis. The prevalence of Von Willebrand disease has been estimated to be 1-3% of the general population. Approximately 80% of Von Willebrand disease patients have a type I deficiency. The laboratory diagnosis of Von Willebrand disease may require both quantitative and qualitative (functional) determinations. PRINCIPLE OF THE TEST REAADS VWF:Ag assay is a sandwich ELISA. A capture antibody specific for human VWF is coated to 96-microwell polystyrene plates. Diluted patient plasma is incubated in the wells, allowing any available VWF:Ag to bind to the anti-human VWF antibody on the microwell surface. The plates are washed to remove unbound proteins and other plasma molecules. Bound VWF:Ag is quantitated using horseradish peroxidase (HRP) conjugated anti-human VWF detection antibody. Following incubation, unbound conjugate is removed by washing. A chromogenic substrate of tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2) is added to develop a colored reaction. The intensity of the color is measured in optical density (O.D.) units with a spectrophotometer at 450nm. Patient VWF:Ag in relative percent concentration is determined against a curve made from the reference plasma provided with the kit. Refer to product package insert.

Recalls

Date	Firm	Reason
2026-07-29	Diagnostica Stago, Inc.	A positive drift in QC values within the reagent's stated 4-hour onboard stability period was identified
2026-02-04	Diagnostica Stago, Inc.	The potential of out-of-range results and an underestimation of the free protein S level in normal patient plasmas. The defect only affects normal-range values.
2023-02-01	Aniara Diagnostica LLC	New warnings and precautionary statements on product labelling: Reagent 2 (R2) of BIOPHEN Protein C 5 contains the chemical substance - Cesium Chloride which changed classification
2020-03-04	Diagnostica Stago, Inc.	A risk of sample-to-sample cross-contamination of Emicizumab for factor VIII assays on Stago instruments, clotting times will be shortened that may cause factor VIII levels report
2017-04-04	Helena Laboratories, Inc.	Internal components of the Protein S ELISA Antigen Kit (Lot: 3-16-5292) were mislabeled. The Protein S Conjugate Solution is labeled as Substrate, and the Substrate is labeled as
2015-12-18	Instrumentation Laboratory Co.	This Lot is not meeting labeled on-board instrument stability claims of 5 days.
2015-11-19	Siemens Healthcare Diagnostics, Inc.	Factor VIII Chromogenic Assay Lot 44637 is showing an increased occurrence of irregular curves when used for measurement on Sysmex CA-1500, CA-7000, CS-2000i, CS-2100i, CS-5100 Sys
2012-10-24	Sekisui Diagnostics Llc	Spectrolyse PAI-1 activity assay, producing lower than expected absorbance values 0 IU/ml standard reducing the slope of the standard curve requiring more frequent sample dilutio
2012-08-28	Sekisui Diagnostics Llc	SPECTROLYSE PAI-1 activity assay producing lower than expected absorbance values with "0" standard. This will reduce the slope of the standard curve requiring the user to make mor
2012-04-11	Instrumentation Laboratory Co.	Falsely elevated levels may be reported with the HemosIL von Willebrand Factor Activity assay.

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Data compiled from public U.S. FDA sources (GUDID, 510(k)/PMA, MAUDE, recalls, establishment registration). Adverse-event reports are unverified and do not establish causation. Informational only — not medical, clinical, or regulatory advice.