5900 Activated Protein C Resistance

Components
NAME METHOD REFERENCE RANGE UNITS
APCR Ratio CLOT DET  > 2.22   
APCR Interpretation   By Report   


Specimen Requirements
TYPE VOLUME TEMPERATURE INSTRUCTIONS
PRIMARY
1 Plasma Citrated 2 (0.5) mL   Frozen - 14 Day(s) See COLLECTION INSTRUCTIONS for platelet-poor plasma. 


Clinical utility
Screening test for FV Leiden, with sensitivity approaching 100%. APCR is the most commonly recognized abnormality among patients with venous thromboembolism. Homozygous Factor V Leiden patients have a 3-140-fold increased risk for thrombosis; heterozygous patients have a 3-8-fold increased risk. The presence of other thrombotic risk factors may modify these risks.


Collection Instruction
Patient should be at rest before drawing blood. Sensitivity and
specificity for FV Leiden are not affected by Coumadin. The assay
allows for analysis of plasma from heparinized patients at heparin
levels < or equal to 1 IU/mL, unfractionated or LMW. Presence of
Antiphospholipid Antibodies can cause inaccurate APCR results.
Care should be taken to avoid contact activation of samples since
this may lead to activation of FV and FVIII.
Instructions for platelet-poor plasma:
Draw a plain red top tube to remove tissue fluid contamination.
Discard this tube.
Draw blood into a buffered citrate collection tube (light blue
top) filled to proper level. Do not overfill.
The blood-to-anticoagulant ratio should be 9:1; inadequate
filling of the collection device will decrease this ratio and
may lead to inaccurate results.
Adjust the final citrate concentration in the blood
of patients who have hematocrit values above 0.55 (55%). For
hematocrits below 20%, there is no current data available to
support a recommendation for adjusting the citrate concentration.
The needle gauge could be between 19-22 (pediatric:
21-23 gauge needle).
Invert gently 6 times to mix. Process immediately.
Centrifuge for 15 min at 2500 x g.
Remove plasma using a plastic pipette.
Repeat centrifugation at 2500 x g for 15 minutes to assure
complete platelet removal.
Dispense the plasma into 2 or more plastic tubes using a
plastic transfer pipette.
Freeze immediately. Stable for 2 months at -20 C and 6 months at
-70 C.
Specimen must remain frozen at all times. Ship to Specialty
within 24 hours on dry ice.
Specimen should not be submitted if: it is hemolyzed; microclots
are present; the tube is less than 90% filled; a specimen
with hematocrit >55% is collected without anticoagulant
adjustment.


Reported: Same day

CPT Code: 85307