Chromogenic Factor VIII Inhibitor

Label Mnemonic:	CH8IN
Epic code:	LAB9508
Downtime form:	Doctor/Provider Orders - Pathology Core and Specialty Care Nursery

Hemostasis/Thrombosis
6240 RCP
356-3573

Specimen(s):

Plasma

Collection Medium:

	and
Light Blue top tube 2.7 mL (Na Citrate)	and	Light Blue top tube 2.7 mL (Na Citrate)

Minimum:

Collect TWO Full tubes - 2.7 mL light blue top

Rejection Criteria: Short drawn tube, clot, traumatic tap (excessive hemolysis).

Delivery Instructions:

Deliver to laboratory immediately after collection.

Turn Around Time:

24-48 hours

Reference Range:

<0.5 BU

Comments:

The chromogenic factor VIII inhibitor must be ordered with a chromogenic factor VIII activity assay. The inhibitor will not be performed if the activity assay is ≥ 25%. The chromogenic factor VIII inhibitor assay utilizes bovine factor X and human thrombin and factor IXa. It is insensitive to emicizumab, but may yield unreliable results in the presence of direct oral anticoagulants (dabigatran, rivaroxaban, apixaban), high concentrations of heparin (>2 IU/mL), strong lupus anticoagulants (ratio >1.8), or the Mim8 bispecific antibody.

Methodology:

Chromogenic Bethesda Titer

CPT Code:

85335