Factor VIII Activity

Single-analyte tests

• Factor VIII Activity 086264

  Plasma · Fasting not stated · Turnaround 2 - 3 days

  Method and collection

  Method

  The assay consists of the measurement of the clotting time, in the presence of cephalin and activator, in a system in which all the factors are present and in excess except factor VIII, which is derived from the sample being tested. Testing coagulation factor activities requires that three dilutions be assayed and analyzed to produce a single result.16,17 The slope of the line created by plotting measured factor concentration against sample dilution is evaluated to discern the presence of inhibitors giving rise to nonparallelism.17 Moreover, samples producing results on initial dilution falling outside the analytic measurement range of the assay are tested at additional dilutions to produce reportable results.

  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.

  Collection

  Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.2,3 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 unless the sample is collected using a winged (butterfly) collection system. With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.4,5 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 alternative 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. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• Factor VIII Activity With Inhibitor Reflex 086010

  Plasma · Fasting not stated · Turnaround 5 - 7 days

  Method and collection

  Method

  See individual activity test information for method information. The Bethesda titer measures the amount (titer) of an inhibitor antibody against a specific clotting factor.1 The test uses dilutions of the patient's plasma and determines the amount of antibody needed to neutralize 50% of the factor activity provided by pooled normal plasma with results expressed in Bethesda units (BUs). One Bethesda Unit (BU) is defined as the amount of an inhibitor that will neutralize 50% of one unit of the factor in normal plasma after 120 minutes incubation at 37°C. A higher titer indicates a stronger inhibitor, which can significantly impact treatment. A Bethesda titer assay is not performed when factor level exceeds 40% (i.e., in the absence of measurable factor activity inhibition).

  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.

  Collection

  Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.13 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.14,15 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.16,17 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.

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Panels that include this biomarker

• Factor VIII Chromogenic Bethesda Profile, for Patients on Emicizumab 504722

  3 analytes · Plasma · Fasting not stated · Turnaround 5 - 10 days

  Method and collection

  Method

  The Nijmegen modification of the classic Bethesda inhibitor titration assay is used in a chromogenic factor VIII activity setting. Patient sample is heat-inactivated and clarified, then a serial dilution series is prepared in buffered normal plasma containing bovine serum albumin. A chromogenic factor activity is measured to determine residual activity and the inhibitor concentration is determined using an equation that relates the log % residual activity to inhibitor titer.

  Preparation

  The patient should not be anticoagulated. Do not draw from an arm with a heparin lock or heparinized catheter.

  Collection

  Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 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, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.4,5 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 for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• Factor VIII Inhibitor Profile, Comprehensive 117157

  4 analytes · Plasma · Fasting not stated · Turnaround 2 - 3 days

  Method and collection

  Method

  The factor VIII inhibitor (Bethesda titer) assay is performed using an activated partial thromboplastin time (aPTT)-based test system.6 Serial dilutions are made of patient plasma with veronal buffered saline, then mixed with normal plasma containing close to 100% factor VIII activity and are then incubated for one hour. An aPTT-based factor VIII assay using factor VIII-depleted plasma substrate is then performed on these incubated mixtures. Results are compared to those of incubated normal plasma. One Bethesda unit is defined as the amount of factor VIII inhibitor that neutralized 0.5 IU of factor VIII in this system. The number of serial dilutions tested is based on the anticipated level of the inhibitor.

  Preparation

  The patient should not be anticoagulated. Do not draw from an arm with a heparin lock or heparinized catheter.

  Collection

  Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 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, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.4,5 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 for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• Intrinsic Pathway Coagulation Factor Profile 500033

  4 analytes · Plasma · Fasting not stated · Turnaround 2 - 3 days

  Method and collection

  Method

  See individual tests.

  Preparation

  Do not draw from an arm with a heparin lock or heparinized catheter.

  Collection

  Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 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, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.4,5 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 for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• DDAVP (Desmopressin) Challenge Profile 184080

  5 analytes · Plasma · Fasting not stated · Turnaround 5 - 7 days

  Method and collection

  Method

  See individual tests.

  Preparation

  Do not draw from an arm with a heparin lock or heparinized catheter.

  Collection

  This challenge protocol is accomplished as follows: Citrate whole blood is collected (see Sample Collection). This sample should be labeled (Baseline-T0) with the time of collection. Immediately after collecting T0 sample, patient is dosed with DDAVP (Desmopressin) and described in drug labeling. This is not to be done by Labcorp staff. Desmopressin has several side effects, including headache, tachycardia, flushing, hypotension, hyponatraemia, and rarer seizures and coronary events.1,40 ,41 Therefore, the dosing and post-dose status of patients undergoing DDAVP stimulation needs to be carefully monitored by trained clinical personnel.42 One hour after drug dosing, a second citrate whole blood is collected. This sample should be labeled (One Hour-T1) with the time of collection. Three hours later (four hours after drug dosing), a third citrate whole blood is collected. This sample should be labeled (One Hour-T4) with the time of collection. Sample Collection Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.43 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.44,45 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.46,47 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.

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• Menorrhagia Profile 336572

  5 analytes · Plasma · Fasting not stated · Turnaround 2 - 3 days

  Method and collection

  Method

  See individual tests.

  Preparation

  Do not draw from an arm with a heparin lock or heparinized catheter.

  Collection

  Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 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, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.4,5 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 for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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Single-analyte tests

• Factor VIII Activity, Clotting 347

  Plasma · Fasting not stated · Turnaround Set up: Mon-Sat (a.m.)

  Method and collection

  Method

  Photometric Clot Detection

  Collection

  Platelet-poor plasma: Centrifuge light blue-top tube for 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcL). Freeze immediately and ship on dry ice. Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII and von Willebrand Factor studies.

  Reference notes

  50-180 % normal

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• Factor VIII Activity, Clotting with Reflex to Chromogenic Method 70050

  Plasma · Fasting not stated · Turnaround Set up: Wed, Fri

  Method and collection

  Method

  Photometric Clot Detection Reflex: Chromogenic Assay

  Collection

  Platelet-poor plasma: Centrifuge light blue-top tube 15 minutes at approximately 1500 x g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcL). Freeze immediately and ship on dry ice. Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII.

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Panels that include this biomarker

• Factor VIII Inhibitor Panel 40083

  4 analytes · Plasma · Fasting not stated

  Method and collection

  Method

  Chromogenic • Photometric Clot Detection

  Collection

  Submit a total of 4 mL (2 mL in each of 2 tubes). Centrifuge light blue-top tube 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcl). Freeze immediately and ship on dry ice. Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII and von Willebrand Factor studies.

  Reference notes

  Factor VIII Inhibitor, Chromogenic Screen | Negative Factor VIII Activity, Clotting | 50-180 % normal

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• von Willebrand Screen 90271

  6 analytes · Plasma · Fasting not stated

  Method and collection

  Method

  See individual tests

  Collection

  Platelet-poor plasma: Centrifuge light blue-top tube for 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcl). Freeze immediately and ship on dry ice. Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII and von Willebrand Factor studies.

  Reference notes

  See individual tests

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• von Willebrand Disease Panel without Collagen Binding Assay (CBA) 19790

  7 analytes · Plasma · Fasting not stated

  Method and collection

  Method

  See individual tests

  Collection

  Please submit a separate, frozen vial for each special coagulation assay ordered. Draw blood in a light blue-top tube containing 3.2% sodium citrate, mix gently by inverting 3-4 times. Centrifuge 15 minutes at 1500 g within one hour of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial(s). Freeze immediately and transport on dry ice. Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor ViII and von Willebrand Factor studies.

  Reference notes

  See individual tests

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• Menorrhagia Screen without Consultation 19649

  8 analytes · Plasma · Fasting not stated · Turnaround Set up: Varies with assay

  Method and collection

  Method

  Clotting Assay • Immunoturbidimetric • Platelet Agglutination • Photo/Optical • Photometric Clot Detection

  Collection

  Collect blood in 3 sodium citrate (light blue-top) tubes. Tubes must be filled to capacity to insure correct blood to anticoagulant ratio. Centrifuge whole blood at 1500 g for 15 minutes. Avoiding the buffy coat, transfer plasma using a plastic pipette into a new plastic tube and repeat centrifugation. Aliquot plasma using a plastic pipette into 3 new plastic vials and freeze. Specimens must remain frozen during storage and shipment. All requests for coagulation assays should include a brief patient history and other pertinent clinical information.

  Reference notes

  See Laboratory Report

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• Venous Thrombosis Hypercoagulability Panel with Reflex (Warfarin Patient) 11472

  8 analytes · Plasma · Fasting not stated

  Method and collection

  Method

  Chromogenic • Immunoassay (IA) • Polymerase Chain Reaction and Detection • Clot Detection • dRVVT-based Clot Assay

  Collection

  Whole blood sample is for the Factor V Mutation Analysis and Prothrombin (Factor II) Mutation Analysis. Platelet-poor plasma is for remaining tests. Platelet-poor plasma: Centrifuge light blue-top tube 15 minutes at approximately 1500 x g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into six plastic vials. Plasma must be free of platelets (<10,000/mcL). Freeze immediately and ship on dry ice. Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII and von Willebrand Factor studies.

  Reference notes

  See Laboratory Report

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