General Information
Note: For external requests please click Here for Coagulation Disorders request form. Please complete all information fully
Samples that meet the following criteria will not be processed:
- Samples >12 hours old from the time of collection.
- Samples received from other hospital laboratories that have been frozen and thawed.
- Samples which fail the minimum data set.
Assay limitations:
- The presence of immune complexes or other immunoglobulin aggregates in the patient sample may cause an increased non-specific binding and produce false-positives in this assay.
- The results of this assay should not be used as the sole basis for a clinical decision.
- Some low titre, low avidity antibodies may not be detected.
- The PF4:PVS complexes used in this assay may differ slightly from those created by PF4:heparin. Therefore, it is possible that some antibodies could react with PVS complexes that do not react with heparin complexes and vice versa.
- The detection of heparin-associated antibodies does not on its own confirm the diagnosis of HIT.
- Some patients may have naturally occurring antibodies to PF4.
Please note samples MUST be collected into a plain red top tube. Tubes containing serum separator gel are NOT suitable.
Notes
All requests for HIT screening must be approved by a Haematology Consultant
Reference Range
Reference Ranges are dependent upon methodology:
ACUSTAR (primary method): 0-0.99 U/ml. HIT cannot be excluded for results => 1.0 U/ml
HIT ELISA (secondary method, used for VITT cases): >0.4-1.0 weak positive, >1.0 Positive