Heparin Induced Thrombocytopenia: Update

 

By Pradeep K. Bhagat, MD, Interim Chairman, Department of Pathology

 

Effective February 2017, Main Line Health Laboratories is pleased to offer the Heparin Induced Platelet Ab EIA w/reflex Serotonin Release Assay (PF4G). This assay replaces the current method of screening for Heparin-Induced Antibody (HPF4R) by Particle Immuno-Filtration Assay (PIFA).

 

Heparin PF4 by PIFA testing is known to have significantly high false positive results as well as false negative results for the diagnosis of heparin induced Thrombocytopenia.  The Immucor (Genetic Testing Institute Diagnostics) ELISA Assay is a better assay which we have found to have a 96.7% agreement with the Serotonin Release Assay.  In addition, a recent study found Immucor  ELISA assays to have an overall sensitivity of >95% and specificity of >90%.(1)  Laboratory testing for Heparin Induced thrombocytopenia will be available to order as PF4G with reflex to Serotonin Release Assay, PF4G with No Reflex (PF4GN), and Serotonin Release Assay (SRA).

 

Heparin Induced Platelet Ab EIA w/reflex Serotonin Release Assay should be utilized in patients with an intermediate or high pre-test probability of having Type II HIT as determined by a validated scoring tool such as  the “4 T’s score.”  Each time a Heparin Induced Platelet Ab EIA w/reflex Serotonin Release Assay test is ordered in the SmartChart or EPIC system, a 4 T’s score calculator prompt will appear. This module must be completed and the computed score will characterize the patient as low-, intermediate-, or high-risk for having HIT.  There will be a suggestion to reconsider ordering this test if the 4 T score falls into the low probability range.

 

Please forward any questions you may have to Dr. Pradeep Bhagat, Medical Director, Main Line Health Laboratories, at 484-476-3521, or BhagatP@mlhs.org.

 

  1. Nagler M, Bachmann LM, Cate HT, Cate-Hoek A. Diagnostic value of immunoassays for heparin-induced thrombocytopenia: a systematic review and meta-analysis. Blood 2016 Feb 4 Vol 127:546-557
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