Routine: 2 Hours
Urgent: 1 Hour

24 hours, 7 days a week.

3.2% sodium citrate tubes are acceptable provided they are filed to the line on the manufacturers label. Tubes must be full (see comments below). Whole blood specimens are stable up to 4 hours at room temperature. Citrate plasma separated from cells is stable up to 14 days at -20 degrees C.

For referral testing, submit 2 x 1.0 mL frozen platelet-poor citrated plasma. Remove plasma from cells promptly, within 1 hour of draw, to avoid falsely low results due to heparin cofactor II.

Core Lab sodium citrate specimens must be processed and frozen within 2 hours of specimen collection. OHSU clinics must cab specimen to the Core Lab, Hatfield Research Center (HRC), if processing is delayed or not possible on site. Detailed instructions are included in this manual under Specialized Lab Services, Hemostasis & Thrombosis section.

Add blood to the 1.3 mL mark of Pediatric BLUE top tube, 3.2% sodium citrate.

Heparin, Either STD/LMW - Therapeutic Ranges:
Heparin, Unfractionated: 0.30 to 0.70 U/mL
Enoxaparin, LMWH: 0.70 to 1.20 U/mL
Dalteparin, LMWH: 0.70 to 1.20 U/mL
Tinzaparin, LMWH: Therapeutic range not established. Preliminary studies suggest range similar to dalteparin. Clinical correlation required.

Draw volume is critical due to the liquid anticoagulant. Allow tubes to fill by vacuum.

• Tubes with rubber stopper: fill to line on label.
• Tubes with plastic (Hemogard) cap: the fill level is above the top of the label.
• Syringe: do not remove the vacutainer stopper. Insert the needle through the stopper and allow the tube to fill by vacuum. Do not overfill the vacutainer.
• Pediatric tubes have no vacuum. Remove the cap and add blood to the 1.3 mL mark. Do not overfill.

Monitor 4 to 6 hours post-injection.
Methodology: Anti-Xa chromogenic.

Anti-Xa Level
LMW Heparin
Unfractionated Heparin
Standard Heparin
Enoxaparin
Dalteparin
Tinzaparin
Heparin Level