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Test Code APC RESIST Activated Protein Resistance (APTT), Plasma

Additional Codes

Sunrise Clinical Manager (SCM) Orderable:   Activated Protein C Resistance Assay

AllScripts (AEHR) Orderable:  Activated Protein C Resistance Assay


Performing Laboratory

Northwell Health Laboratories


Clottable APTT-Based

Reference Values

≥ 2.20 Ratio

Test Classification and CPT Coding


Specimen Required

Container/Tube: Light blue-top (3.2% sodium citrate) tube and a lavender-top (EDTA) tube

Specimen: Full tubes

Transport Temperature: Lavender top  tube- Room Temperature and follow collection instructions for light blue top tube.

Collection Instructions:


  1. If the light blue top tube is the only tube to be drawn and will be collected using a butterfly set, a “discard” tube (either a plain[non-additive] or light blue) must be partially drawn just to completely fill the collection tubing with blood before collecting the light blue top for testing.  Failure to perform this step will result in an under-filled tube that the laboratory will reject.
  2. Allow blood to fill the tube completely to the line on the tube.  The ratio of blood to anticoagulant is critical in coagulation testing and at least a 90% fill is required.
  3. Immediately mix the specimen by gently inverting the tube 4-6 times to completely mix with the anticoagulant.  Failure to perform this can result in a clotted sample, which is unacceptable for testing1. If there is a delay in transport, spin down, spin plasma again, and send citrate platelet-poor plasma and whole blood. Freeze if there is a delay in transport  Double-centrifuged specimens are critical for accurate results as platelet contamination may cause spurious results.
  4. Consent form required for molecular genetic testing (Factor V Leiden).
  5. Abnormal ratios will reflex to the performance of Factor V Leiden.

Day(s) and Time(s) Performed

 1 - 2  times per week

Computer Interface Code

PDM # 5600054