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Test 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: 13-mm x 75-mm, 5-mL, plastic vials (polypropylene preferred)

Specimen Volume: 2 mL Platelet-poor plasma in 2 13-mm x 75-mm, 5-mL, plastic vials (polypropylene preferred), each containing 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. Within 4 hours of collection , centrifuge and aliquot plasma into a plastic vial, then centrifuge plasma again.

4. Aliquot plasma (1 mL per aliquot) into 2 13-mm x 75-mm, 5-mL, plastic vials (polypropylene preferred)leaving 0.25 mL in the bottom of centrifuged vial.

5. Immediately freeze plasma (no longer than 2 hours after processing) at -20° C or, ideally, at -40° C or below.

Additional Information:

1. Double-centrifuged specimens are 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

Disease States

  • Hemophilia A

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. To add on FVIII inhibitor testing, call 800-533-1710 within 7 days to assess if adequate plasma sample is available.

 

For more information see Hemophilia Testing Algorithm.

Method Name

Chromogenic

Reporting Name

Chromogenic FVIII, P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

Platelet-poor plasma: 0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Na Cit Frozen 14 days

Reject Due To

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

Clinical Information

Factor VIII (FVIII) is synthesized in the endothelial cells of the liver and, perhaps, in other tissues. It is a coagulation cofactor that circulates bound to von Willebrand factor and is part of the intrinsic coagulation pathway. The biological half-life is 9 to 18 hours (average is 12 hours).

 

Congenital FVIII deficiency is inherited in a recessive X-linked manner and results in hemophilia A, which has an incidence of 1 in 10,000 live male births. Patients with severe deficiency (<1%) experience spontaneous bleeding episodes (eg, hemarthrosis, deep-tissue bleeding), whereas patients with moderate or mild deficiency (>1%) typically experience post-trauma or surgical bleeding.

 

Factor VIII activity assays (FVIII:C) are performed to diagnose hemophilia A and to monitor FVIII replacement therapy. FVIII:C assays are typically 1-stage clotting assays. However, there is a subset of patients with mild hemophilia A who have shown discrepantly low results when measured with the 2-stage (chromogenic) assay, indicating that testing patients with a mild bleeding history with both a 1- and 2-stage assay would aid in diagnosis. In addition, there are new treatment options using long-acting glycoPEGylated products. Pharmacokinetic studies are showing that ideal monitoring of patients should be performed by the 2-stage chromogenic assay.

Reference Values

55.0-200.0%

Reference values apply to all ages.

Interpretation

Factor VIII deficiency may be seen in congenital hemophilia A, acquired (autoimmune) hemophilia A, or von Willebrand disease (congenital and acquired). Laboratory artifacts that may result in artificially reduced factor VIII include specimens collected in EDTA, instead of citrate, or heparin contamination of the plasma specimen.

 

Elevated factor VIII may be seen in acute or chronic inflammatory states or excess factor VIII replacement therapy.

Day(s) Performed

Monday through Friday

Report Available

1 to 3 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

85130

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CHF8 Chromogenic FVIII, P 49865-9

 

Result ID Test Result Name Result LOINC Value
CHF8 Chromogenic FVIII, P 49865-9

Forms

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