Draw blood in a light blue-top (sodium citrate) tube(s). Spin down and send 0.5 mL citrated plasma frozen in plastic vial.

Note: 1) The sample should be drawn 3 hours after injection of drug in order to compare to published peak levels.

         2) Specimen must be spun, separated and frozen within four hours of collection.

         3) This test is only valid for monitoring patients on Arixtra (fondaparinux), not unfractionated heparin or low molecular weight heparin.