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Labcorp Oklahoma, Inc.
Test Directory


Index:

Activated Partial Thromboplastin Time (aPTT)

Order Name PTT
Test Number: 1500050
Revision Date 10/08/2024
Test Name Methodology LOINC Code
Activated Partial Thromboplastin Time (aPTT)
Clot Detection 3184-9 
SPECIMEN REQUIREMENTS
Specimen Specimen Volume (min) Specimen Type Specimen Container Transport Environment
Preferred 2.7 mL Whole Blood Sodium Citrate 3.2% (Blue Top) Room Temperature
Alternate 1 1.5 mL Double Spun Plasma Sterile, Capped Plastic Tube Frozen
Instructions Please indicate anticoagulant therapy. 
Each 2.7mL Sodium Citrate 3.2% (Blue Top) tube must be filled to the proper level, no hemolysis. Improperly filled tubes can give erroneous results.
Whole blood must be transported to lab immediately.
If testing cannot be started within 4 hours of collection the specimen must be double spun then 1.5 mL plasma aliquot from each tube into individual plastic aliquot tubes and freeze.
Do not pool aliquots together!
Specimen Stability: Un-Frozen specimens are only good for 4 hours. If the patient is on Heparin, Un-Frozen specimens are only good 2hrs.
GENERAL INFORMATION
Testing Schedule Mon-Fri 
Expected TAT From Set Up  
Clinical Use This test is most commonly used to monitor heparin therapy. It is also prolonged with deficiencies of clotting factors of the intrinsic system and the common pathway. Presence of antifactor antibodies, and other inhibitors may also be detected with this test. 
CPT Code(s) 85730
Lab Section Coagulation