Activated Protein C Resistance


Abbrev Code:APCR   
Order Code:LAB3286Order Name:Activated Protein C Resistance
Synonyms:APCR; Resistance to Activated Protein C
Methodology:PTT's on patient and normal plasma containing Factor 5 deficient plasma with and without addition of Activated Protein C. Activated Protein C (APC) ratio is reported.
CPT Codes: 85307 x1, 85307 x1
Turnaround Time:Turnaround time is 7 days, testing performed 1 day per week (Thursday or Friday). With pre-notification, STATs are done within 1 hour after receipt in the testing laboratory.
Associated Links:

Specimen Collection and Processing for Coagulation Specimens


Collection Instructions

Specimen:Blood
Optimal Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube.
Minimum\Peds Volume:1.8 mL (in 2 mL tube) - filled to fill line on the tube.
Container:Blue Na Citrate, 3.2% - fill to fill line on tube
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tubes, overfilled tubes, clotted specimens, not received or processed and frozen within 4 hours of collection or, specimen thawed during transit.


Processing and Shipping

Specimen Processing:
  • Process for Platelet Poor Plasma within 4 hours of collection.
  • Aliquot plasma, place clear tape around label, and freeze at -20C or on dry ice within 4 hours of collection.
  • If multiple tests are collected on 1 blue top, split each blue top into 2 aliquots. Minimum 0.5 mL per tube.
  • A maximum of 6 aliquots are needed per collection.

See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:
  • Ensure specimen is frozen before shipping.
  • Ship on dry ice, sample must remain frozen during shipping.

See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab UM Special Coag (K)  (UMMC East Bank)


Interpretive

Reference Range:APC Ratio (>1 year old): >2.12 Age specific reference ranges have not been established for patients 0-1 years old.
Limitations:Test CAN be performed on patients on Vitamin K antagonist (warfarin, Coumadin) and/or unfractionated heparin. Testing should not be performed on patients on direct thrombin inhibitors (e.g. argatroban, dabigatran) or direct factor Xa inhibitors (e.g. rivaroxaban, apixaban).
Use:
Functional clotting test for resistance to activated Protein C. Up to 90% of activated Protein C resistance is caused by Factor 5 Leiden mutation which can be detected using genetic testing.
  • If APCR is positive, Factor 5 Leiden genetic testing is recommended.
  • If APCR is positive and Factor 5 Leiden is negative, APCR is likely due to another mutation (10-15% of cases).
  • If APCR is negative, it is unlikely a Factor 5 mutation causing resistance to activated Protein C is present.


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