To evaluate an isolated prolonged APTT and to document specific factor IX deficiency.

• Ideally the patient should not be on anticoagulant therapy.
• Avoid warfarin (Coumadin®) therapy for two weeks prior to the test and heparin, direct Xa, and thrombin inhibitor therapies for about three days prior to testing.

Lt blue Sodium citrate (NaCit)

• Do not draw from an arm with a heparin lock or heparinized catheter.
• Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.
• Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.
• The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood.
• A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system.
  • With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.
• When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternative anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes.
• If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted.

Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp)

Frozen - 28 days

Freeze/thaw cycles - stable x3

• Severe hemolysis
• Improper labeling
• Clotted specimen
• Specimen diluted with I.V. fluids
• Samples thawed in transit
• Improper sample type
• Sample out of stability

Factor IX activity is determine utilizing an aPTT-based one-stage clotting time assay. Factor IX-depleted plasma is used as the substrate, and the clotting time with the patient plasma is compared to the clotting time of normal pooled plasma.

60 - 177%