Specimen Collection Manual and Test Catalog

1 mL plasma aliquot for a single factor study. Each additional factor study requires an additional 0.5 mL aliquot. Samples requiring heparin neutralization require an additional 0.5 mL for each factor.

• If the patient’s hematocrit (HCT) is >55%, the volume of anticoagulant in the tube must be adjusted. Contact a performing location for sodium citrate adjusted tubes or instruction for how to adjust the sodium citrate.
• When possible, use fresh venipuncture.
• Avoid prolong tourniquet time (< 1 minute) and hemolysis during collection as this will alter results.
• If indwelling catheter or butterfly collection device must be used, draw sample from a non-heparinized lumen or flush the line with 5 mL of saline and discard the first 10 mL of blood.
• Tubes should be >90% filled.
• Immediately mix gently after collection by inverting the tube end over end 5 to 6 times. Avoid vigorous mixing or additional inversion. Observe for the presence of clots or hemolysis and recollect if observed.

Centrifuge specimen immediately at designated time and speed to obtain platelet-poor plasma (<10,000/µL). Using a plastic pipette, carefully remove plasma from cells, avoiding platelet/buffy layer by leaving a thin layer of plasma on top the cells. The centrifuged plasma should be aliquoted (1 mL per aliquot) into clearly labeled polypropylene tubes. The number of tests ordered will determine the aliquots needed. Check the residual specimen for clot and if present discard sample and redraw specimen. If plasma is icteric, lipemic or hemolyzed a lab comment should be generated to notify staff. Freeze upright in non-thaw freezer.

Frozen on dry ice

Room temperature (whole blood): 4 hours 
Room temperature (plasma off cells): 8 hours 
Frozen (plasma) -20°C: 2 weeks 
Frozen (plasma) -70°C: 6 months 
 

Clotted, hemolyzed, improperly filled tubes, improper anticoagulant ratio (HCT >55% and citrate not adjusted), refrigerated specimens, or stability exceeded. 

Note: Specimen suspected of thawing in transport, indicated by slant in aliquot or specimen in lid of tube, will have testing performed, and the comment “interpret results with caution as thawing suspected” added to results.

83-117%

Anticoagulation Impact on Coagulation Tests

Factor II activity

Factor II, Factor 2, FA2

Factor II or prothrombin is converted to thrombin which is necessary for normal clot formation. It is part of the common clotting cascade, is made in the liver and requires vitamin K for its synthesis. Low levels can result in a bleeding disorder. Factor II levels are decreased in patients with congenital deficiencies (rare), acquired factor II antibodies (rare), vitamin K antagonist (warfarin), vitamin K deficiency from poor oral intake, malabsorption, or improper metabolism (hemorrhagic disease of newborn, cholestasis, certain antibiotic therapy), liver disease, and DIC. Factor II activity assay can be useful in evaluating the reason for both a prolonged PT and aPTT with normal thrombin time.

This assay should not be used to assess the patient’s risk of thrombosis. Please order the Prothrombin Gene Mutation (PGM) if that is the desired test. Pathology will investigate all orders for a Factor II assay to determine correct order practice.