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Test Code LAB3377 APTT Heparin Neutralization

Important Note

Specimen tube must be full. The ratio of blood to anticoagulant is critical. Increased or decreased volumes of anticoagulant will cause erroneous results.

Test Name Alias

Activated Partial Thromboplastin Time (APTT) | APTT Heparin Neutralization

Panel Information

APTT

Heparin Neutralized PTT

Collection Instructions

Specimen Collection: Blood

 

Container(s): 4.5 mL Blue top (3.2% Na. Citrate) or 1.8 mL Clear/Blue top (3.2% Na. Citrate Pediatric)

Preferred Volume to Collect: 4.5 mL (Tube must be full)

Minimum Volume to Collect: 1.8 mL (Pediatric Tube must be full)

Capillary collect ok: No

Microtainer acceptable: 1.8 mL clear/blue top must be full

 

Collection Instructions:

  • Please indicate anticoagulant therapy.

  • Detailed instructions: Blue Citrate Tube

  • Obtain venous blood by clean venipuncture.

  • If specimen is collected using a line, then 5.0 mL waste is required, this waste can be given back.

  • Avoid leaving the tourniquet on the patient’s arm for an extended period prior to collection.

  • Tube must be full. Do not over fill or under fill; look for the fill indicator lines.

  • Gently invert 8 – 10 times to mix anticoagulant with blood.
  • Specimen should be processed within 4 hours – See Processing Instructions.
  • Specimen collected from patients receiving heparin therapy must be centrifuged within 1 hour —See Processing Instructions 

Processing Instructions (Laboratory, Outpatient or Off-site collection)

Processed Specimen: Platelet Poor Plasma

Centrifuge/Spin: Yes

Aliquot: Yes

 

Processing Instructions:

  • Centrifuge and remove plasma within 4 hours of collection. Specimen collected from patients receiving heparin therapy must be centrifuged within 1 hour.

    • To obtain a Coagulation plasma sample, centrifuge the capped specimen tube at a speed and time required to consistently produce platelet-poor plasma (platelet count < 10,000/uL). The centrifugal speed and duration to accomplish this must be established by the individual laboratory. Our laboratories use centrifuges at 3,000 to 4,000 rpm for ten minutes or higher speed and shorter duration centrifuges.

    • When removing plasma to send to Coagulation it is important NOT to go all the way down to the cells. Leave a minimum 1/4 inch of plasma sitting on cells. This layer contains platelets which were separated from the plasma during spinning. The platelets interfere with Coagulation testing so we leave this layer undisturbed.

  • Separate plasma into 1 – 2 aliquots, minimum of 0.5 mL in each tube.
  • Freeze aliquots in plastic transport tubes immediately.

Transport Temperature:

  • Ambient (up to 1 – 4 hours in whole blood state)
  • Frozen (plasma only >1 hour post collection)

Rejection Criteria

  • Hemolysis
  • Thawed

Specimen Stability

Ambient: Whole Blood: 1 – 4 hours (depending on if patient is on Heparin Therapy)

Frozen: 2 months

Laboratory Retention: 24 hours

Test Frequency

Available 24 hours, usual TAT 1 day.

Reference Range

21-32 seconds

Clinical Information

For use as a heparin neutralizer in plasma to rule out heparin contamination in coagulation testing.

Reflex Information

Initial Test and Result Confirmation Testing/Additional Workup
APTT Mixing Study APTT and, if the APTT Mixing Study does not correct, order a Lupus Anticoagulant Screen (LA1)
aPTT Mixing Studies (Test Code 4120) greater than or equal to 6 seconds above the normal range. Heparin Neutralization (Policy 6679) to rule out anticoagulant:
  • If aPTT corrects to normal, then a Mixing Study is not indicated.
  • If aPTT remains elevated, then Unfractionated Heparin Level (Test Code 8101) assay is ordered.
    • If Unfractionated Heparin Level is greater than 1.0 U/mL, then a Mixing Study is not indicated.

 

Performing Department

Coagulation

Performing Department Laboratory Location

Spectrum Health Regional Laboratory, Grand Rapids, MI

Methodology

Heparinase cleaves heparin at multiple sites per molecule.  Hepzyme can neutralize up to 2 USP units of unfractionated heparin in 1 mL of citrated plasma.

CPT

Not available

CDM Code

Not available

Interface Order Alias

11684

Mayo Access Code

Not available

LOINC

Not available

Reviewed Date

6/1/2017