Test Details
Methodology
Enzyme-linked immunosorbent assay (ELISA)
Result Turnaround Time
5 - 7 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
This test is used for the measurement of the amount of factor VIII protein (not activity) of factor VIII to identify individuals that are cross-reacting material (CRM)-positive.
Special Instructions
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions.
Limitations
Factor VIII is an acute phase reactant and can be elevated in a number of clinical conditions. This can affect the accuracy of the test in diagnosing hemophilia. Factor VIII levels should not be used to determine the carrier status of females. Genetic testing should be used for this purpose. Factor VIII inhibitors (both autoantibodies that develop after replacement therapy and autoantibodies that develop spontaneously) can result in low factor VIII levels.
Assay interference due to the presence of drugs or due to the presence of heterophilic antibodies such as Lupus Anticoagulant (LA) has not been reported; however, the potential for interference by high levels of heterophilic antibodies cannot be excluded. The presence of Rheumatoid Factor in test samples will cause interference in the assay. The theoretical possibility of test samples containing antibodies to sheep immunoglobulin may also interfere in the assay.
Custom Additional Information
The factor VIII (FVIII) is an essential cofactor for factor IX (FIX) and plays a key role in the intrinsic pathway of the coagulation cascade.1-4 Upon tissue injury, FVIII potentiates activated FIX (FIXa) activity to form the intrinsic FXase (tenase) complex, which is responsible for the activation of factor X (FXa) generated by the coagulation cascade. FXa then combines with activated factor V (FVa) to form the FXa/FVa prothrombinase complex, which converts prothrombin to thrombin. Thrombin cleaves fibrinogen, to form fibrin monomers, and activates factor XIII (FXIIIa), which catalyzes the formation of covalent bonds between fibrin monomers and a stabilized fibrin clot.
The laboratory diagnosis of Factor VIII deficiency typically involves quantitative determinations based on procoagulant levels (functional activity of Factor VIII typically measured by clotting assay). Clinical bleeding symptoms may also be used in the diagnosis and classification, however, the quantitative procoagulant measurement is the preferred method of classifying the severity of hemophilia. FVIII antigen may be used in conjunction with the functional to distinguish those patients that may be deemed cross-reacting material (CRM)-positive. Some hemophiliacs produce a FVIII protein that is partially or totally inactive.5 In these cases, FVIII activity is low but the FVIII antigen levels are normal or near normal. These patients, comprising approximately 5% of Hemophilia A patients, are termed (CRM)-positive.6
Specimen Requirements
Specimen
Plasma, frozen
Volume
1 mL
Container
Blue stopper 3.2% sodium citrate plasma evacuated tube
Collection Instructions
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.7 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.8,9 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples.10,11 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge and carefully remove the plasma using a plastic transfer pipette, being careful not to disturb the cells. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
Reference Range
64–189%
Storage Instructions
Freeze.
Patient Preparation
Ideally, the patient should not be on anticoagulant therapy. Avoid warfarin (Coumadin®) therapy for two weeks prior to the test and heparin, direct Xa and thrombin inhibitor therapies for about three days prior to testing. Do not draw from an arm with a heparin lock or heparinized catheter.
References
Sarmiento Doncel S, Díaz Mosquera GA, Rico CA, Cadavid FJM, Peláez RG. Haemophilia A: A Review of Clinical Manifestations, Treatment, Mutations, and the Development of Inhibitors. Hematol Rep. 2023 Feb 16;15(1):130-150. PubMed 36810557
Spena S, Garagiola I, Cannavò A, et al. Prediction of factor VIII inhibitor development in the SIPPET cohort by mutational analysis and factor VIII antigen measurement. J Thromb Haemost. 2018 Apr;16(4):778-790. PubMed 29399993
Trossaërt M, Regnault V, Sigaud M, Boisseau P, Fressinaud E, Lecompte T. Mild hemophilia A with factor VIII assay discrepancy: using thrombin generation assay to assess the bleeding phenotype. J Thromb Haemost. 2008;6(3):486-493. PubMed 18047548
Footnotes
1. Mehta P, Reddivari AKR. Hemophilia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan. 2023 Jun 5. PubMed 31869071
2. Bowyer AE, Gosselin RC. Factor VIII and Factor IX Activity Measurements for Hemophilia Diagnosis and Related Treatments. Semin Thromb Hemost. 2023 Sep;49(6):609-620. PubMed 36473488
3. Müller J, Miesbach W, Prüller F, et al. An Update on Laboratory Diagnostics in Haemophilia A and B. Hamostaseologie. 2022 Aug;42(4):248-260. PubMed 35104901
4. Lee C, Berntorp E, Hoots W. Textbook of Hemophilia. 2nd ed. Chichester, UK: Blackwell Publishing Ltd; 2010.
5. Nair PS, Shetty S, Ghosh K. Factor VIII Antigen, Activity, and Mutations in Hemophilia A. Clin Appl Thromb Hemost. 2016 May;22(4):381-385. PubMed 25550078
6. Amano K, Sarkar R, Pemberton S, Kemball-Cook G, Kazazian HH, Kaufman RJ. The molecular basis for cross-reacting material-positive hemophilia A due to missense mutations within the A2-domain of factor VIII. Blood. 1998 Jan 15;91(2):538-548. PubMed 9427707
7. Adcock DM, Kressin DC, Marlar RA. Effect of 3.2% vs 3.8% sodium citrate concentration on routine coagulation testing. Am J Clin Pathol. 1997 Jan;107(1):105-110. Pubmed 8980376
8. Reneke J, Etzell J, Leslie S, Ng VL, Gottfried EL. Prolonged prothrombin time and activated partial thromboplastin time due to underfilled specimen tubes with 109 mmol/L (3.2%) citrate anticoagulant. Am J Clin Pathol. 1998 Jun;109(6):754-757. PubMed 9620035
9. National Committee for Clinical Laboratory Standardization. Collection, Transport, and Processing of Blood Specimens for Coagulation Testing and General Performance of Coagulation Assays; Approved Guideline. 5th ed. Villanova, Pa: NCCLS; 2008. Document H21-A5:28(5).
10. Gottfried EL, Adachi MM. Prothrombin time and activated partial thromboplastin time can be performed on the first tube. Am J Clin Pathol. 1997 Jun;107(6):681-683. PubMed 9169665
11. McGlasson DL, More L, Best HA, Norris WL, Doe RH, Ray H. Drawing specimens for coagulation testing: Is a second tube necessary? Clin Lab Sci. 1999 May-Jun;12(3):137-139. PubMed 10539100
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 086015 | Factor VIII Antigen | 38521-1 | 086016 | Factor VIII Antigen | % | 38521-1 |
| Order Code | 086015 | |||||
| Order Code Name | Factor VIII Antigen | |||||
| Order Loinc | 38521-1 | |||||
| Result Code | 086016 | |||||
| Result Code Name | Factor VIII Antigen | |||||
| UofM | % | |||||
| Result LOINC | 38521-1 |