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Test Code LAB325 Activated Partial Thromboplastin Time (APTT)

Collection:

Specimen: Blood 

Container: Blue Top Tube with 3.2% (0.109 M) buffered Sodium Citrate anticoagulant only

Specimen Volume: 3.5 mL Must be filled to arrow (Greiner tube Black Disk) or line (BD)

Pediatric Collection: 2.0 mL Must be filled to arrow (Greiner tube White Disk) or line (BD)

Notes: 

  • Samples not filled properly will be rejected (over or under filled).
  • If the patient's hematocrit is >55%, call Lab Client Services at 792-0707 to obtain an anticoagulant adjusted tube.
  • For collection information and guidance refer to  MUSC Laboratory Services Hemostasis / Coagulation Collection Guidelines.

Stability:

Non-Heparinized Patients:

  • Room Temperature: 4 hours Whole Blood
  • Refrigerated: 4 hours Whole Blood
  • Frozen at or below -20°C: 2 weeks

Heparinized Patients:

  • Room Temperature: 2 Hours Whole Blood
  • Refrigerated: 2 hours Whole Blood
  • Frozen at or below -20°C: 2 weeks 

Note: Frozen samples must be platelet poor plasma aliquoted from primary tube. Label as Na Citrate or blue top plasma.

Turnaround Time (TAT):

OR/Trauma: 40 minutes

STAT: 1 HOUR

Routine: 3 HOURS

Test Availability:

Daily / 24 Hours / Available STAT

Performing Laboratory Section:

COAGULATION / UMC MAIN LABORATORY

Reference Interval:

</=30 days (full term infant): 34.0 - 51.2 sec
>30 days - Adult: 25.6- 36.0 sec

Interpretive Data:

Reference ranges for infants less than or equal to 30 days are for full term healthy infants only. Call laboratory (792-0707) to obtain reference range values for premature healthy infants.
The Activated Partial Thromboplastin time (aPTT) is to be used for monitoring Direct Thrombin Inhibitor Therapy. The therapeutic range for these anticoagulants is 1.5 - 2.5 times the patient's base line aPTT.

The recommended aPTT therapeutic range for the treatment of Deep Vein Thrombosis (DVT) or Pulmonary Embolus (PE) using Unfractionated Heparin is
61 - 105 seconds which is equivalent to 0.3 - 0.7 Anti-Xa units/ml.
..........
Brill Edwards correlation of anti-Xa level to aPTT is as follows:
..........
Anti-Xa (U/mL) = aPTT (seconds)
0.1 U/mL = 43.0 seconds
0.2 U/mL = 52.3 seconds
0.3 U/mL = 61.0 seconds
0.4 U/mL = 73.1 seconds
0.5 U/mL = 83.6 seconds
0.6 U/mL = 94.0 seconds
0.7 U/mL = 105.0 seconds
0.8 U/mL = 114.9 seconds
0.9 U/mL = 125.3 seconds
1.0 U/mL = 135.7 seconds