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Test Code PTT Activated Partial Thromboplastin Time (APTT, PTT), Plasma

Performing Laboratory

Huntsville Hospital Laboratory/Madison Hospital Laboratory


Mechanical Clot Detection

Specimen Requirements

1. Draw blood in a blue-top (citrate) tube(s). Spin down, remove plasma, spin plasma again, and place 0.5 mL of citrate platelet-poor plasma in plastic vial. (Glass vial is not acceptable.)
Note:  Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. Freeze specimen immediately at ≤-40° C, if possible.
3. Send specimen frozen.
Note:  Each coagulation assay requested should have its own vial.

Specimen Stability Information


Specimen Type Temperature Time
Citrate plasma Room Temperature, Spun 4 hrs
  Room Temperature, Spun for PTTH 2 hrs


Reject Due To


Hemolysis Mild: OK unless patient on Heparin Gross: Reject
Lipemia Mild: OK Gross: OK
Icterus Mild: OK Gross: OK


Reference Values

27-39 seconds
Critical values

Anticoagulated:  >200 seconds

Non-anticoagulated:  >60 seconds

Day(s) Test Set Up

Monday through Sunday

CPT Coding


LOINC Coding

Test Name LOINC Code

Activated Partial Thromboplastin Time (APTT, PTT), Plasma