Activated Protein C Resistance


Sunquest Code:APCR  
Epic Code:LAB3286Epic 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 Code:85307
Turnaround Time:Specimen is accepted and processed 24 hours/day, 7 days/week. Test is performed once per week; results are reported within 7 days.
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.
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tubes or clotted specimens


Processing and Shipping

Specimen Processing:See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab Special Coagulation  (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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