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.
Optical Clot-Based
Hemlibra
EMICIZ
Emicizumab
Plasma Na Cit
If priority specimen, mark request form, give reason, and request a call-back.
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 degrees C or, ideally, at -40 degrees 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.
If not ordering electronically, complete, print, and send an Coagulation Test Request (T753) with the specimen.
0.5 mL
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Plasma Na Cit | Frozen | 42 days |
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.
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.)
<1 mcg/mL
Therapeutic ranges for plasma emicizumab concentrations have not been established. Trough plasma concentrations observed during clinical trials ranged between 35 and 55 micrograms/mL.
The presence of endogenous and exogenous factor VIII (approximately > 10% [>0.1 IU/mL] by bovine chromogenic FVIII assay) will cause the emicizumab level to be falsely elevated.
Excess heparin and dilution contamination due to improper specimen collection through an intravenous access device may result in artifactually decreased results.
Aliquot tubes should be made with non-activating material, such as polypropylene (Aliquot Tube, 5 mL [T465]).
1. Knight T, Callaghan MU. The role of emicizumab, a bispecific factor IXa- and factor X-directed antibody, for the prevention of bleeding episodes in patients with hemophilia A. Ther Adv Hematol. 2018;9(10):319-334. doi:10.1177/2040620718799997
2. Jenkins PV, Bowyer A, Burgess C, et al. Laboratory coagulation tests and emicizumab treatment A United Kingdom Haemophilia Centre Doctors' Organisation guideline. Haemophilia. 2020;26(1):151-155. doi:10.1111/hae.13903
3. Jonsson F, Schmitt C, Petry C, Mercier F, Frey N, Retout S. Exposure-response modeling of emicizumab for the prophylaxis of bleeding in hemophilia A patients with and without inhibitors against factor VIII. Poster PB0325 presented at: The XXVII Congress of the International Society on Thrombosis and Haemostasis. July 6-10, 2019; Melbourne, Australia
4. Pipie SW, Shima M, Lehle M, et al. Efficacy, safety and pharmacokinetics emicizumab prophylaxis given every 4 weeks in people with haemophilia (HAVEN 4): a multicenter, open-label, non-randomized phase 3 study. Lancet Haematol. 2019;6(6):e295-e305. doi:10.1016/S2352-3026(19)30054-7
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)
Monday through Friday
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.
80299
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
EMICZ | Emicizumab, modified OSA FVIII, P | 99614-0 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
EMICZ | Emicizumab, modified OSA FVIII, P | 99614-0 |