Activated Partial Thromboplastin Time




Test Mnemonic

PTT

CPT Codes

  • 85730 - QTY (1)

LOINC ®

14979-9

Aliases

  • Activated Partial Thromboplastin Time
  • APTT
  • Partial Thromboplastin Time

Performing Laboratory

n/a


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1 mLPlasmaSodium citrate (Lt. Blue) Centrifuge, aliquot and freeze ASAP.Collection tube must be filled to total fill volume. Inadequately filled tubes will be rejected. NonTesting Sites: Centrifuge, aliquot platelet poor plasma into a separate tube with Epic Beaker label, freeze plasma at -20C, send frozen plasma to Main Campus on dry ice.
1.8 mLWhole bloodSodium citrate (Lt. Blue) Centrifuge, aliquot and freeze ASAP.Collection tube must be filled to total fill volume. Inadequately filled tubes will be rejected. NonTesting Sites: Centrifuge, aliquot platelet poor plasma into a separate tube with Epic Beaker label, freeze plasma at -20C, send frozen plasma to Main Campus on dry ice.

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
N/A    Collection tube must be filled to total fill volume. Inadequately filled tubes will be rejected.

Stability

Environmental Condition Description
Ambient4 hours
RefrigeratedUnacceptable
Frozen14 days at -20 C; 6 months at -70 C

Days Performed

Sun - Sat

Turnaround Time

8 hours

Methodology

Name Description
Automated Optical Clot Detection 

Reference Range

Activated PTT
Sex Age From Age To Type Range Range Unit
   Days1 DaysNormal27.1 - 43.7sec
 2 Days5 DaysNormal22.0 - 48.0sec
 6 Days30 DaysNormal22.1 - 44.3sec
 1 Months3 MonthsNormal20.8 - 40.2sec
 4 Months11 MonthsNormal24.3 - 34.4sec
 1 Years99 YearsNormal23.0 - 32.4sec
   Years99 YearsUrgent> 100.0sec
   Years99 YearsCriticalEXTREMELY ABNORMAL RESULT. No clot detected at 320 seconds. Refer to anticoagulation nomogram for further actions. 

Special Info

Collection tube must be filled to total fill volume. Inadequately filled tubes will be rejected. Specimens with hematocrit values > 55% have spuriously increased APTT values. To correct for this, specimens should be re-collected using a specified whole blood to sodium citrate ratio. Contact the performing lab for specific instructions.

Clinical Info

Evaluation of hemostasis.

Clinical Limitation

n/a

Clinical Reference

n/a