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HelpOrder Code CHF8 Chromogenic Factor VIII Activity Assay, Plasma
Ordering Guidance
Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, a coagulation consultation is recommended.
Necessary Information
Specimen Required
Specimen Type: Platelet-poor plasma
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Specimen must be collected prior to factor replacement therapy.
2. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing
3. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
4. Aliquot plasma into plastic vial leaving 0.25 mL in the bottom of centrifuged vial.
5. 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.
Useful For
Monitoring coagulation factor replacement therapy of selected extended half-life coagulation factor replacements
Aiding in the diagnosis of hemophilia A using a 2-stage assay, especially when the 1-stage assay result was normal
Testing Algorithm
This assay is indicated in situations where there is a clinical suspicion of hemophilia A diagnosis, but the 1-stage factor VIII (FVIII) assay result is normal. However, recent guidelines recommend this assay be performed in addition to the 1-stage assay in the initial workup of hemophilia A.
Testing for autoantibodies to FVIII in the presence of a low FVIII activity may be clinically indicated. For adding on FVIII inhibitor, call 800-533-1710 within 7 days to assess if adequate plasma sample is available.
For more information see Hemophilia Testing Algorithm.
Special Instructions
Method Name
Chromogenic
Reporting Name
Chromogenic FVIII, PSpecimen Type
Plasma Na CitSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Cit | Frozen | 14 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
| IV heparin contamination | Reject |
Reference Values
55.0-200.0%
Chromogenic factor VIII activity generally correlates with the one-stage FVIII activity. In full term/premature neonates, infants, children, and adolescents the one-stage FVIII activity* is similar to adults. However, no similar data for chromogenic FVIII activity are available.(Appel IM, Grimminck B, Geerts J, Stigter R, Cnossen MH, Beishuizen A. Age dependency of coagulation parameters during childhood and puberty. J Thromb Haemost. 2012;10(11):2254-63)
*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing
Method Description
The Chromogenic Factor VIII assay is performed on the Instrumentation Laboratory ACL TOP Family using the CRYOcheck Chromogenic Factor VIII kit. In this 2-stage assay, patient plasma is diluted and combined with reagents containing bovine factor X, human factors IXa and IIa, calcium chloride, and phospholipids. The factor VIII in the patient's plasma aids in the activation of factor X to factor Xa. After a specified incubation period, chromogenic substrate is added at which time, the factor Xa, present from the previous step, hydrolyzes the substrate into peptide and p-nitroaniline (pNA). The color produced by the release of pNA is measured photometrically at 405 nm and is proportional to the factor VIII in the sample.(Package insert: CRYOcheck Chromogenic Factor VIII. Precision BioLogic Inc; Rev V04, 06/2020)
Day(s) Performed
Monday through Friday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
85130
Forms
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.