HIT or miss? A comprehensive contemporary investigation of laboratory tests for heparin induced thrombocytopenia

Emmanuel J Favaloro, Georgia McCaughan, Soma Mohammed, Kun Kan Edwin Lau, Rosalie Gemmell, Lauren Cavanaugh, Dea Donikian, Mayuko Kondo, Timothy Brighton, Leonardo Pasalic

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

Heparin induced thrombocytopenia (HIT) is a rare but potentially fatal complication of heparin therapy, which in a proportion of patients causes platelet activation and thrombosis. Initial clinical assessment of the likelihood of HIT is facilitated by laboratory testing to confirm or exclude HIT. This prospective investigation was performed over an 18-month period, and has involved testing of over 300 test samples from over 100 consecutive patients. Clinical assessment by 4T score was supplemented by laboratory tests that comprised both immunological [lateral flow ('STiC'), chemiluminescence (AcuStar; HIT-IgG(PF4-H)), ELISA (Asserachrom HPIA IgG)] and functional assays [SRA, platelet aggregation using whole blood ('Multiplate') and platelet rich plasma ('LTA')]. We observed both false positive and false negative test findings with most assays. Overall, the whole blood aggregation method provided a reasonable alternative to SRA for identifying functional HIT. STiC, AcuStar and ELISA procedures were fairly comparable in terms of screening for HIT, although STiC and AcuStar both yielded false negatives, albeit also resulting in fewer false positives than ELISA. The 4T score had less utility in our patient cohort than we were expecting, although there was an association with the likelihood of HIT. Nevertheless, we accept that our observations are based on limited test numbers. In conclusion, no single approach (clinical or laboratory) was associated with optimal sensitivity or specificity of HIT exclusion or identification, and thus, a combination of clinical evaluation and laboratory testing will best ensure the accuracy of diagnosis.

Original languageEnglish
Pages (from-to)426-436
Number of pages11
JournalPathology
Volume50
Issue number4
Early online date17 Apr 2018
DOIs
Publication statusPublished - Jun 2018

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