Laboratory Medicine Program

Bethesda Inhibitor (Nijmegen)
(Factor Inhibitor Studies)

Clinical Decription:
Bethesda units (BU) are a standardized method of quantifying acquired or specific clotting factor inhibitors. The BU level correlates with antibody inhibitor titer. A BU is the amount of antibody activity required to inhibit 0.5 units of factor VIII activity. This is a critical assay for the identification and monitoring of inhibitors to Factors VIII and IX and of limited utility for other specific factor inhibitors.

Method: Optical Clot Detection; Siemens Sysmex CS-5100

Component Tests Used: Factor Assay, Bethesda Inhibitor studies

Reference Ranges Used:
< 0.5 BU

Specimen Type: Citrated plasma
Collected In: 3.2% Sodium Citrate
Volume: 2 x 1.0 mL (minimum: 2 x 1.0 mL)

Shipping: Send frozen on dry ice.

Special Instructions: Patient should be fasting, if possible. The specimen must be double-centrifuged to obtain a platelet-poor plasma specimen (Plt <10x10E9/L): 1. Immediately centrifuge specimen at 1500xG for 10 minutes. 2. Separate the plasma from the platelet/buffy coat and transfer into a clean plastic tube. 3. Centrifuge the separated plasma at 1500xG for 10 minutes. 4. Transfer 1.0 to 2.0 mL of the double-centrifuged plasma into a clean plastic tube, leaving approx. 200 uL for discard. 5. Freeze plasma aliquot immediately for storage. Maintain frozen for shipping and handling.

Testing Schedule(s): Weekly.

Turnaround Time: 2 days

Download order form

For more information, call 416.340.5227 or 1.866.865.5227

Back to Search