Collect specimens in 4 blue top (citrate 3.2%) tubes. Mix by inversion. Specimens should arrive at the lab within 3 hours of collection; transport at room temperature. Alternatively, centrifuge, aliquot plasma into 4 plastic tubes, and freeze the specimen within 4 hours of collection. Transport frozen specimens on dry ice. Collection of the blood through lines that have been previously flushed with heparin should be avoided. If the blood must be drawn through a VAD (vascular access device), the line should be flushed with 5 mL of saline and the first 5 mL of blood or six dead space volumes of the VAD discarded.

Please provide clinical history (brief description of the reason for testing, eg. history of recent or remote thromboembolism, family history of hypercoagulability) and a listing of current and recent medications, including oral contraceptives, and anticoagulants.