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Test ID 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

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

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 in Special Instructions.

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, ≤-40° C.

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 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 is normal. However, recent guidelines also 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.


See Hemophilia Testing Algorithm in Special Instructions.

Method Name


Reporting Name

Chromogenic 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 14 days

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, etc), whereas patients with moderate or mild deficiency (>1%) typically experience post-trauma or surgical bleeding.


FVIII 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



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 JTH 2012;10:2254)


*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.


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 samples collected in EDTA, instead of citrate, or heparin contamination of the plasma sample.


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

Clinical Reference

1. Rodgers SE, Duncan EM, Sobieraj-Teague M, Lloyd JV: Evaluation of three automated chromogenic FVIII kits for the diagnosis of mild discrepant haemophilia A. Int J Lab Hematol. 2009 Apr;31(2):180-188

2. Kitchen S, Beckman H, Katterle Y, et al: BAY 81-8973, a full-length recombinant factor VIII: results from an International comparative laboratory field study. Haemophilia. 2016 May;22(3):e192-199. doi: 10.1111/hae.12925

3. Peyvandi F, Oldenburg J, Friedman KD: A critical appraisal of one-stage and chromogenic assays of factor VIII activity. J Thromb Haemost. 2016 Feb;14(2):248-261

4. Dodt J, Hubbard AR, Wicks SJ, et al: Potency determination of factor VIII and factor IX for new product labelling and postinfusion testing: challenges for caregivers and regulators. Haemophilia. 2015 Jul;21(4):543-549

Day(s) Performed

Monday through Friday

Report Available

1 to 3 days

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


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


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