Test Library

Preferred Specimen(s) One full 3.2% sodium citrate (light blue-top) tube

Instructions A completely filled tube is necessary because the correct ratio of blood to citrate is critical (9:1). Mix by gentle inversion 3-4 times. Do not uncap. Stable 2 days at room temperature. If the specimen will be delayed longer than 2 days, centrifuge the specimen for 15 minutes at 1500 RCF (relative centrifugal force). Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet (buffy) layer and place into a plastic screw-cap vial and freeze at – 20o C. Ship on dry ice.

Transport Container

Whole blood: 3.2% sodium citrate (light blue-top) tube

Plasma: Plastic screw-cap vial (frozen)

Transport Temperature Room temperature: (Light blue-top) tube (whole blood) Frozen: Plasma

Reject Criteria

  • Gross hemolysis
  • Improper blood to citrate ratio
  • High hematocrit
  • Improper blood collection

Methodology Clotting Method

Clinical Significance Screening test for abnormalities of coagulation factors that are involved in the extrinsic pathway. Also used to monitor effect of Coumadin® anticoagulants and study the patients with hereditary and acquired clotting disorders.