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Test Code HEPA Unfractionated Heparin Assay by Anti - Xa

Specimen Type

Plasma

Container/Tube

Light blue top tube, 3.2% sodium citrate

Offsite Collection Instructions

  • Samples must be centrifuged at >2500 x g for 10 minutes
    at room temperature.
  • Carefully remove the plasma from the cells using a plastic
    transfer pipette avoiding the buffy coat.
  • Dispense the plasma into a plastic tube (glass is not
    acceptable) and centrifuge the plastic tube for a second
    centrifugation at >2500 x g for 10 minutes at room
    temperature.
  • Remove the top portion of the plasma being careful to leave
    a small amount of plasma at the bottom of the tube undisturbed
    (about 250mL). Then, aliquot the removed plasma into 2 plastic tubes
    containing minimum of 500 uL of specimen each.
  • The plasma samples must then be frozen at -20 C.
  • Once solidly frozen they must be shipped on dry ice.
    Samples that have thawed in transit will be rejected.

 

Note: For clients who do not have access to dry ice do not
freeze the specimen. Follow the centrifugation instructions or
send whole blood sample. It now becomes vital that the centrifuged
specimen arrives in the lab within four hours of blood
collection. Whole blood must arrive within one hour of
collection.

Turnaround Time

4 hours

Preferred Volume

1 mL

UCMC Collection Instructions

Samples may be collected and sent to the lab at any time.

Please note that testing for unfractionated
heparin level may be added on to an existing order only up to
one hour following the time of blood draw due to technical
considerations of this assay.

Additional Information

All 3.2% citrate tubes require a ratio of 9 parts blood to 1
part anticoagulant (Example: a 3.0 mL tube requires 2.7 mL
blood added to 0.3 mL of anticoagulant).
 

Unfractionated heparin level is monitored by functional
anti-Xa
assay.
For monitoring of heparin therapy the frequently employed
target
range is 0.3-0.7 anti-Xa Units/mL (e.g., for treatment of
venous thrombosis). For the lower intensity anticoagulation
range
of aPTT 50-70 seconds (e.g., as in guidelines from American
College
of Chest Physicians), the corresponding
range is currently 0.13-0.41 anti-Xa Units/mL.

Fee Code

30585520

Synonyms

Anti-Xa

Unfractionated heparin by anti-Xa

Heparin level

Heparin level by anti-Xa

 

Test Usage

Monitoring of unfractionated heparin in settings where aPTT
is unreliable.

Critical Results

n/a

STAT Turnaround Time

n/a

Specimen Minimum Volume

0.5 mL

DAY(S) AND TIME(S) PERFORMED

Testing is performed 7 days a week from 8:00 am to 11:00 pm.
Samples received after 11:00 pm will be run the following day.

STAT DAY(S) AND TIME(S) PERFORMED

Not Available

CPT

85520

Method Name

Chromogenic

Reject Due To

Specimens that have wrong ratio of blood to anticoagulant
(fill volume) clotted or grossly hemolyzed.