Specimen Requirements

• See “Coagulation Studies—Billings Clinic Laboratory” under "Resources".
• Draw blood in a light blue-top (3.2% sodium citrate) tube(s).
• Immediately after draw, gently invert tube(s) at least 6 times to mix well.
• Spin down, remove plasma, spin plasma again, and place 2 mL of citrate platelet-poor plasma in plastic vial.
• Glass vial is not acceptable.
• Freeze specimen immediately at -20° C.
• Send specimen frozen.
• Double-centrifuged specimens are critical for accurate results as platelet contamination may cause spurious results.
• Patient should not be on Coumadin® or heparin.
• Correction of the anticoagulant to blood ratio is required for patient hematocrits <20% or >55% for the light blue-top tube.