INR

Panels that include this biomarker

• Prothrombin Time (PT) 005199

  2 analytes · Plasma · Fasting not stated · Turnaround Within 1 day

  Method and collection

  Method

  Prothrombin time reagent containing thromboplastin and calcium chloride is mixed with the patient plasma and the time to clot formation is measured photo-optically. The calcium chloride overcomes the citrate anticoagulant and allows the tissue factor in the thromboplastin to initiate coagulation. The prolongation of the clotting time correlates with the degree of deficiency or inhibition of the extrinsic pathway factors.

  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.

  Reference notes

  See table. Age | Range13-15 Prothrombin Time (PT) 1 day | 14.4−16.4 sec 3 days | 13.5−16.4 sec 1 to 11 m | 11.5−15.3 sec 1 to 5 y | 12.1–14.5 sec 6 to 10 y | 11.7−15.1 sec 11 to 16 y | 12.7−16.1 sec >16 y | 12.2 –14.9 sec International Normalized Ratio (INR) 0 to 1 m | 0.9−1.4 >1 m | 0.9−1.2

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• Prothrombin Time (PT) (Serial Monitor) 485199

  2 analytes · Specimen not stated · Fasting not stated · Turnaround Within 1 day

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• Prothrombin Time (PT) and Partial Thromboplastin Time (PTT) 020321

  3 analytes · Plasma · Fasting not stated · Turnaround Within 1 day

  Method and collection

  Preparation

  Draw specimen one hour before next dose of heparin if heparin is being given by intermittent injection. 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.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. 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 notes

  See table. Age | Range6-8 Activated Partial Thromboplastin Time (aPTT) 1 d | 29–38 sec 3 d | 25−36 sec 1 to 11 m | 30−39 sec 1 to 5 y | 29−37 sec 6 to 10 y | 27–37 sec 11 to 16 y | 25–34 sec >16y | 23–34 sec Prothrombin Time (PT) 1 d | 14.4−16.4 sec 3 d | 13.5−16.4 sec 1 to 11 m | 11.5−15.3 sec 1 to 5 y | 12.1–14.5 sec 6 to 10 y | 11.7−15.1 sec 11 to 16 y | 12.7–16.1 sec >16y | 12.2–14.9 sec International Normalized Ratio (INR) 0 to 1 m | 0.9−1.4 >1 m | 0.9−1.2

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• Abnormal Bleeding Profile 116004

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

  Method and collection

  Method

  See individual tests.

  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.

  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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• Drug-Induced Liver Injury Profile 010045

  6 analytes · Serum · Fasting not stated · Turnaround Within 1 day

  Method and collection

  Method

  See individual tests.

  Collection

  Serum or plasma: Separate serum or plasma from cells within 45 minutes of collection. PT with INR blood: Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio. 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. 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. Print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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