Protein C-Functional

Single-analyte tests

• Protein C, Functional 117705

  Plasma · Fasting not stated · Turnaround 2 - 3 days

  Method and collection

  Method

  Protein C in plasma is activated by a specific enzyme (protein C activator) from copperhead snake venom ( Agkistrodon contortrix ). The amount of activated protein C is determined. The resulting activated PC (Protein Ca) is determined as the rate of hydrolysis of a chromogenic substrate in a kinetic test by measuring the increase in absorbance at 405 nm.

  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, except when the sample is collected using a winged (i.e., "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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Panels that include this biomarker

• Protein C Deficiency Profile 283655

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

  Method and collection

  Method

  PC antigen: enzyme immunoassay (EIA) PC activity: A specific enzyme extracted from the venom of Agkistrodon c. contortrix is used to activate PC in the patient sample. All other factors required for normal aPTT are supplied in the reagent. The activated protein C inhibits factors V and VIII in the reagent and the resultant prolongation of the aPTT-based clotting time is proportional to plasma PC activity.

  Preparation

  Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior to the test. 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.

  Reference notes

  PC levels tend to be lower in newborns but typically reach adult ranges by six months of age.6 Levels in some children remain low until up to 16 years of age.6

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• Thrombotic Risk, Congenital 117140

  3 analytes · Plasma · Fasting not stated · Turnaround 3 - 7 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 anti-coagulant with the blood. A discard tube is not required prior to collection of coagulation samples except when using a winged blood collection device (i.e., "butterfly"), in which case a discard tube should be used.4,5 When non-citrate 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 recentifuge for 10 minutes. Use a second plastic pipette to remove 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. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested. It is important to centrifuge blood samples for plasma collection immediately after collection to separate the plasma from the blood cells. If immediate centrifugation is not possible, collected blood specimens should be kept on ice and centrifuged within an hour. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• Thrombotic Risk, Congenital (Extended) 117185

  6 analytes · Serum · Fasting not stated · Turnaround 3 - 7 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 anti-coagulant with the blood. A discard tube is not required prior to collection of coagulation samples except when using a winged blood collection device (i.e., "butterfly"), in which case a discard tube should be used.4,5 When non-citrate 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 recentifuge for 10 minutes. Use a second plastic pipette to remove 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. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested. It is important to centrifuge blood samples for plasma collection immediately after collection to separate the plasma from the blood cells. If immediate centrifugation is not possible, collected blood specimens should be kept on ice and centrifuged within an hour. Other plasma : It is important to centrifuge blood samples for plasma collection immediately after collection to separate the plasma from the blood cells. If immediate centrifugation is not possible, collected blood specimens should be kept on ice and centrifuged within an hour. Serum: Sample should be centrifuged as soon as possible after collection to avoid false elevation of homocysteine and transported in a completely separated gel barrier-tube (SST) or transfer tube. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• Thrombotic Risk Assessment 117155

  14 analytes · Serum · Fasting not stated · Turnaround 3 - 7 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 anti-coagulant with the blood. A discard tube is not required prior to collection of coagulation samples except when using a winged blood collection device (i.e., "butterfly"), in which case a discard tube should be used.4,5 When non-citrate 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 recentifuge for 10 minutes. Use a second plastic pipette to remove 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. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested. It is important to centrifuge blood samples for plasma collection immediately after collection to separate the plasma from the blood cells. If immediate centrifugation is not possible, collected blood specimens should be kept on ice and centrifuged within an hour. Serum: If a red-top tube is used, transfer separate serum to a plastic transport tube. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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