PF4/heparin antibody testing and treatment of heparin-induced thrombocytopenia in the intensive care unit

Clin Appl Thromb Hemost. 2013 Jun;19(3):297-302. doi: 10.1177/1076029612438709. Epub 2012 Mar 2.


Background: The diagnosis of heparin-induced thrombocytopenia (HIT) may be challenging in critically ill patients, as heparin exposures are ubiquitous, and thrombocytopenia is common. Unwarranted ordering and incorrect interpretation of heparin antibody tests can expose a patient to adverse drug events and imposes a significant economic burden on our health care system.

Methods: A prospective, observational study was performed over 4 months on all adult patients located in 5 intensive care units, with a heparin antibody test ordered.

Results: A platelet factor 4/heparin enzyme-linked immunosorbent assay (ELISA) test was ordered in 131 patients. In total, 110 patients had a low 4Ts score (0-3), and of these 103 had a negative ELISA result. In patients with a low 4Ts score, 0 (0%) of 110 had an optical density value >1.0. One hundred twenty-nine patients (98%) had another possible cause of thrombocytopenia identified.

Conclusion: In critically ill patients, low 4Ts scores indicate a low probability of HIT, and heparin antibody testing in these patients is not useful.

Keywords: HIT; PF4/heparin; heparin; heparin antibody test; heparin-induced thrombocytopenia; thrombocytopenia.

MeSH terms

  • Adult
  • Aged
  • Antibodies / blood*
  • Anticoagulants / adverse effects*
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Heparin / adverse effects*
  • Heparin / immunology
  • Humans
  • Intensive Care Units
  • Male
  • Middle Aged
  • Platelet Factor 4 / immunology*
  • Prospective Studies
  • Thrombocytopenia / chemically induced*


  • Antibodies
  • Anticoagulants
  • Platelet Factor 4
  • Heparin