Factor XIII Activity

Single-analyte tests

• Factor XIII Activity 086340

  Plasma · Fasting not stated · Turnaround 4 - 6 days

  Method and collection

  Method

  FXIII contained in the sample is converted by the action of thrombin into FXIIIa. Fibrin formed by thrombin also accelerates this reaction. Fibrinogen is not removed prior to testing since this would cause a loss of FXIII. Instead, fibrin produced by the action of thrombin is prevented from forming clots by an aggregation inhibiting peptide and held in solution. FXIIIa cross-links a specific peptide substrate to glycine ethyl ester, thereby releasing ammonia. The ammonia released is then determined in a parallel enzymatic reaction. The decrease in NADH is measured by monitoring the absorbance at 340 nm.

  Collection

  Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.20 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.21,22 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.23,24 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.

  Reference notes

  43–148%

  Labcorp catalog page

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Single-analyte tests

• Factor XIII, Functional 14461

  Plasma · Fasting not stated · Turnaround Set up: Thurs (a.m.)

  Method and collection

  Method

  Chromogenic

  Collection

  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/uL). Freeze immediately and ship on dry ice. Note oral anticoagulant therapy

  Reference notes

  57-192 % activity

  Quest Diagnostics catalog page

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