Test Name


Specimen Type & Acceptability

Whole Blood – Blue Top Sodium Citrate Tube
48 hours from the time of collection stored at room temperature

General Use

Evaluate the extrinsic system and common pathway in the clotting mechanism.

Aids in screening for congenital and acquired deficiencies of factors II, V, VII, X, and fibrinogen. This test is used clinically for the therapeutic monitoring of warfarin (Coumadin®) anticoagulant therapy.

CPT Code(s)


Special Instructions

Light blue sodium citrate tubes should be collected and allowed to fill completely. The tubes should NOT be opened, spun, refrigerated or frozen & must be received in the lab within 24 hours of collection at room temperature.
Light blue sodium citrate tubes can be spun within 24 hours, the platelet-poor plasma aliquoted, placed in a transport/aliquot tube and frozen for shipment. The specimen must be shipped on dry ice and received in the lab completely frozen or it will be rejected.

Container/Tube Type


0.5 mL from a full 2.7 mL Sodium Citrate Tube

Suggested Tube Types


Typical Volume

Gold Top Serum Separator Tube (SST)

⋜ 5 mL

Tiger Top Serum Separator Tube (SST)
^For larger volume tests

> 5 mL

Red Top Tube (No additive)

⋜ 5 mL

EDTA Whole Blood

3 mL

3.2 % Sodium Citrate Whole Blood

2.7 mL

Lithium Heparin Plasma Separator Tube

⋜ 5 mL