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Test Code EMICZ Emicizumab, Modified One Stage Assay Factor VIII, Plasma


Ordering Guidance


For monitoring factor VIII infusions or diagnosing hemophilia, order F8A / Coagulation Factor VIII Activity Assay, Plasma.



Necessary Information


If priority specimen, mark request form, give reason, and request a call-back.



Specimen Required


Specimen Type: Platelet-poor plasma

Patient Preparation: For at least 12 to 24 hours before specimen collection, the patient should not be given infusions of factor VIII concentrates.

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

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

Submission Container/Tube: Plastic vial (polypropylene preferred)

Specimen Volume: 1 mL

Collection Instructions:

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

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

3. Aliquot plasma into a plastic vial, leaving 0.25 mL in the bottom of centrifuged vial.

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


Secondary ID

610074

Useful For

Monitoring compliance or potential development of an antidrug antibody

 

This assay is not indicated for monitoring factor VIII infusions or for making a diagnosis of hemophilia.

Disease States

  • Hemophilia A

Method Name

Optical Clot-Based

Reporting Name

Emicizumab, modified OSA FVIII, P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 42 days

Clinical Information

Emicizumab (Hemlibra) is a bispecific antibody directed toward factor IXa and factor X, bridging in close enough proximity to mimic and replace factor VIII. Emicizumab has been approved by the US Food and Drug Administration for prevention of bleeding in hemophilia A patients, both with and without inhibitors to factor VIII.

 

In clinical trials, clinical outcomes were achieved without the measurement of plasma emicizumab levels to inform and make management decisions. However, in selected clinical situations, measurement of drug level would be useful. (eg, for patients experiencing break through bleeding episodes, if levels are not detectable or below the published [observed] ranges, this may imply noncompliance or development of an antidrug antibody.)

Reference Values

<1 mcg/mL

Interpretation

Therapeutic ranges for plasma emicizumab concentrations have not been established. Trough plasma concentrations observed during clinical trials ranged between 35 and 55 micrograms/mL.

Method Description

The emicizumab (Hemlibra) assay is a modification to the one stage factor VIII assay performed on the Instrumentation Laboratory (IL) ACL TOP using the activated partial thromboplastin time (IL SynthASil APTT) method and a factor-deficient substrate. Patient plasma is combined and incubated with a factor VIII-deficient substrate (Precision Biologic, normal plasma depleted of factor VIII by immunoadsorption) and an APTT reagent. After a specified incubation time, calcium is added to trigger the coagulation process in the mixture. Then the time to clot formation is measured optically at a wavelength of 671 nm and interpolated against a drug specific calibration.(Owen CA Jr, Bowie EJW, Thompson JH Jr. Diagnosis of bleeding disorders. 2nd ed. Little, Brown and Company; 1975; Cielsa B. Defects of plasma clotting factors. In: Hematology in Practice. 3rd ed. FA Davis; 2019:chap 17)

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

80299

LOINC Code Information

Test ID Test Order Name Order LOINC Value
EMICZ Emicizumab, modified OSA FVIII, P 99614-0

 

Result ID Test Result Name Result LOINC Value
EMICZ Emicizumab, modified OSA FVIII, P 99614-0

Day(s) Performed

Monday through Friday

Forms

If not ordering electronically, complete, print, and send an Coagulation Test Request (T753) with the specimen.

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.