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Prolonged Activated Partial Thromboplastin Time (aPTT)

CPT: 85240; 85250; 85270; 85280; 85613; 85732
Updated on 07/10/2019
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Synonyms

  • Intrinsic Factors

Test Includes

Factor VIII; factor IX; factor XI; factor XII; lupus anticoagulant with reflex


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.

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.

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.


Expected Turnaround Time

2 - 3 days


Related Information


Related Documents

For more information, please view the literature below.

Procedures for Hemostasis and Thrombosis: A Clinical Test Compendium


Specimen Requirements


Specimen

Plasma, frozen


Volume

3 mL


Minimum Volume

2 mL


Container

Blue-top (sodium citrate) tubes


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.


Storage Instructions

Freeze.


Patient Preparation

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


Causes for Rejection

Tube improperly filled; improper labeling; clotted specimen; hemolysis; thawed specimen


Test Details


Use

Diagnose patients suspected of having a bleeding disorder due to a coagulation deficiency


Methodology

See individual tests.


Contraindications

Patient on anticoagulant therapy

Footnotes

1. 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. 8980376
2. 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. 9620035
3. 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).
4. 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. 9169665
5. 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. 10539100

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
117796 Prolonged APTT 086264 Factor VIII Activity % 3209-4
117796 Prolonged APTT 086298 Factor IX Activity % 3187-2
117796 Prolonged APTT 086314 Factor XI Activity % 3226-8
117796 Prolonged APTT 086322 Factor XII Activity % 3232-6
117796 Prolonged APTT 117003 PTT-LA sec 34571-0
117796 Prolonged APTT 117891 dRVVT sec 6303-2
117796 Prolonged APTT 117893 Lupus Reflex Interpretation 75514-0
Reflex Table for PTT-LA
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 117040 PTT-LA Mix 117005 PTT-LA Mix sec 75510-8
Reflex 2 117020 Hexagonal Phase Phospholipid 117842 Hexagonal Phase Phospholipid sec 3282-1
Reflex Table for PTT-LA
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 117040 PTT-LA Mix 117005 PTT-LA Mix sec 75510-8
Reflex 2 117035 PTT-LA Incub Mix 117036 PTT-LA Incub Mix sec 50760-8
Reflex 3 117020 Hexagonal Phase Phospholipid 117842 Hexagonal Phase Phospholipid sec 3282-1

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