Suspected HIT |
- Platelet count – Low
- Heparin-PF4 assays – Not yet available
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Acute HIT (confirmed diagnosis) |
- Platelet count – Low
- Heparin-PF4 assays – Positive (functional assays and/or immunoassays)
|
Subacute HIT A (platelet count recovered but persistent HIT antibodies) |
- Platelet count – Recovered to normal or patient's baseline
- Heparin-PF4 assays – Positive (functional assays and immunoassays)
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Subacute HIT B (persistent HIT antibodies but functional assay no longer positive) |
- Platelet count – Recovered to normal or patient's baseline
- Heparin-PF4 assays – Functional assay has become negative (after previously being positive); immunoassay remains positive
|
Remote HIT (HIT resolved, but patient remains at risk for developing acute HIT) |
- Platelet count – Normal or patient's baseline
- Heparin-PF4 assays – Negative (after previously being positive)
|