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HIT-Ab (LAB001949)
Test Mnemonic:


Specimen Requirements:

Fill within ±10% from stated capacity. Immediately after draw, gently invert 3-4 times.


3.2% tri-sodium citrate (light blue-top) and serum separator tubeRoutine venipuncture; discard 1st mL of blood by collecting a discard tube prior to collecting the blue-topped (3.2% sodium-citrate) tube.  For collections with butterfly blood collection sets, a discard tube should also be collected prior to collection of the blue top to ensure sufficient sample volume. Drawing a discard tube will displace the air from the blood collection set tubing to ensure proper blood draw volume



Blue-topped (3.2% sodium-citrate) tube and SST (HIT-SST) tube are required

Minimum Volume:

0.5 mL of plasma  

1.0 mL of Serum


In-house samples must be sent at room temperature avoiding extremes of temperature. When transported by pneumatic tube, specimens should be protected from vibrations and shock. Off-site samples must be centrifuge and transport specimens frozen.


Plasma: Ambient - 4 hours; Refrigerated - Unacceptable; Frozen at -20 °C for up to 2 weeks; -70°C for 6 months 

Serum: Ambient - Unacceptable; Refrigerated - 1 week; Frozen - Indefinitely

Causes for Rejection:
  1. Clotted and hemolyzed plasma samples are unacceptable and must be redrawn.
  2. Wrong tube or anticoagulant.
  3. Wrong anticoagulant ratio (over or underfilled tubes).
  4. Not centrifuged within the acceptable time after collection.
  5. Whole blood or plasma refrigerated or placed on ice prior to testing.
  6. Unlabeled.
  7. Mislabeled.
  8. Plasma that is grossly hemolysis, partially coagulated (presence of micro-clots), damaged by temperature changes or with bubbles on its surface may cause inaccurate results.
Reference Range:

HIT Antibody negative   < 1.0 U/mL

HIT Antibody positive    > 1.0 U/mL

Turnaround Time:

24 hours/ 7 days a week - 4 hours TAT


Immunoturbidimetric assay


Samples are accepted 24 hours per day at Sample Management, 7.412 CSW Bldg.




HIT IGG, HAT, Heparin Induced Antibodies, HIT Antibodies, Heparin-associated antibody, Heparin PF4 Antibody

CPT 4 Code:


When ordering tests for which Medicare or Medicaid reimbursement will be sought, physicians should only order tests that are medically necessary for the diagnosis or treatment of the patient. Components of the organ or disease panels may be ordered individually. The diagnostic information must substantiate all tests ordered and must be in the form of an ICD-10 code or its verbal equivalent.
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