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Test Code CH8B Chromogenic Factor VIII Inhibitor Bethesda Titer, Plasma


Specimen Required


Only orderable as part of a profile. For more information see CHF8P / Chromogenic Factor VIII Inhibitor Bethesda Profile, Plasma.

Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vials

Specimen Volume: 2 mL in 2 plastic vials, each containing 1 mL

Collection Instructions:

1. Specimen must be collected prior to factor replacement therapy.

2. If collecting sample through a port/line, be sure to waste the appropriate amount prior to collection.

3. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.

4. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

5. Aliquot plasma (1 mL per aliquot) into 2 separate plastic vials leaving 0.25 mL in the bottom of centrifuged vial.

6. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally -40° C or below.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.


Useful For

Detecting the presence and titer of a specific factor inhibitor directed against coagulation factor VIII

 

This test is not useful for detecting the presence of inhibitors directed against other clotting factors and will not detect the presence of lupus anticoagulants.

Method Name

Only orderable as part of a profile. For more information see CHF8P / Chromogenic Factor VIII Inhibitor Bethesda Profile, Plasma.

 

Chromogenic

Reporting Name

Chromogenic FVIII Inhibitor Titer,P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject
IV heparin contamination Reject

Clinical Information

Factor VIII (FVIII) inhibitors are IgG antibodies directed against coagulation FVIII that typically result in development of potentially life-threatening hemorrhage. These antibodies may be alloimmune: developing in patients with congenital FVIII deficiency (hemophilia A) in response to therapeutic infusions of factor VIII concentrate or autoimmune: occurring in patients without hemophilia (not previously factor VIII deficient) either spontaneously, during pregnancy, or in association with autoimmune diseases.

Reference Values

Only orderable as part of a profile. For more information see CHF8P / Chromogenic Factor VIII Inhibitor Bethesda Profile, Plasma.

 

≤0.5 Bethesda Units

Interpretation

The interpretive report will include assay information, background information, and conclusions based on the test results.

Cautions

Contamination with excess heparin and hemodilution due to improper specimen collection through an intravenous access device or collection above a running intravenous fluid line may cause spurious results.

Method Description

In the Bethesda procedure, patient plasma is heat-inactivated (HI) at 56° C for 30 minutes. Next using the HI patient plasma, serial dilutions are prepared and mixed in equal volumes with normal pooled plasma. The mixture is incubated 2 hours at 37° C. At the end of the incubation, chromogenic factor VIII (CH8) activity is measured and compared to a control performed at the same time. The difference between the CH8 activity of the patient's incubation mixture and that of the control is used to calculate the titer. The residual CH8 activity is converted to Bethesda units: 50% residual CH8 is equal to 1 Bethesda unit. Assays using the same basic principle as the Bethesda assay are used to quantitate the inhibitors of the other coagulation factors.(Favaloro EJ, Lippi G. eds. Hemostasis and Thrombosis: Methods and Protocols. 1st ed. Humana Press; 2017)

Day(s) Performed

Monday through Friday

Report Available

2 days

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

85335

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CH8B Chromogenic FVIII Inhibitor Titer,P 93450-5

 

Result ID Test Result Name Result LOINC Value
CH8B Chromogenic FVIII Inhibitor Titer,P 93450-5