Bethesda Assay for Factor 8 with Normal Plasma


Sunquest Code:BETH2  
Epic Code:LAB3317Epic Name:Bethesda for Factor 8/Norm Plasma
Synonyms:Factor 8 Hemophilia Antibody; Factor 8 Inhibitor; Hemophilia A Inhibitor; Betheda Assay for Factor VIII
Methodology:Measurement of residual Factor 8 on mixtures of patient plasma mixed with normal pooled plasma. Factor 8 Bethesda samples are incubated for 2 hours at 37 C.
CPT Code:----------CPTCODES HERE----------
Turnaround Time:Specimen is accepted and processed 24 hours/day, 7 days/week. Test is performed as needed; results are reported within 2-4 days.
Special Instructions:Indicate on request form when the last Factor 8 infusion was administered. If Thrombin Time is >60 seconds. Bethesda Assay for Factor 8 will be cancelled with the following comment: SPECIMEN CANCELLED, INTERFERING SUBSTANCES DETECTED. CORRELATION WITH MEDICATIONS RECOMMENDED.
Associated Links:

Specimen Collection and Processing for Coagulation Specimens



Collection Instructions

Specimen:Blood
Optimal Volume:Three 3 mL tubes, each containing 2.7 mL blood; each filled to fill line on tube.
Minimum\Peds Volume:Two 3 mL tubes, each containing 2.7 mL blood; each filled to fill line on tube.
Collection Instructions:See link to Specimen Collection and Processing of Coagulation Specimens.
Causes for Rejection:Underfilled tubes or clotted specimens
Contraindications:Factor 8 infusion within last week


Processing and Shipping

Specimen Processing:See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab Special Coagulation  (UMMC-East Bank)


Interpretive

Reference Range:0 Bethesda U/mL
Use:The Bethesda assay is designed specifically to measure the concentration of anti-Factor 8 antibody in patients with hemophilia A. One Bethesda Unit is the amount of antibody that will inactivate 0.5 U/mL (50%) of Factor 8. Patients with "spontaneous" (acquired) antibodies will give variable results because of the unique conditions of the test and the nature of these types of antibodies.


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