The clinical diagnosis of heparin-induced thrombocytopenia in patients receiving continuous renal replacement therapy

Abstract

Background: Thrombocytopenia is common in critically ill patients who receive continuous renal replacement therapy. Often, these patients receive heparin therapy and the diagnosis of heparin induced thrombocytopenia (HIT) is considered as a potential etiology. No data regarding the clinical diagnosis of HIT is available for patients receiving continuous renal replacement therapy.

Patients and methods: We performed a retrospective study of 29 consecutive patients who received CRRT in a medical-surgical intensive care unit (ICU) and determined trends in platelet counts following CRRT and the frequency of meeting platelet based clinical criteria for consideration of a HIT diagnosis.

Results: For patient exposures to CRRT concurrent with heparin, 54% met at least one clinical threshold for consideration of the diagnosis of HIT. In 31% of exposures, both a platelet count <100,000/mm3 and a >50% decrease from baseline were seen. In contrast, the majority (73-85%) of patients receiving CRRT had a low pre-test probability of HIT using the "4T's" scoring system. Mean platelet counts while on CRRT concurrent with heparin were significantly lower than when patients received heparin alone (P < 0.02).

Conclusions: The clinical diagnosis of HIT in ICU patients initiating CRRT is challenging given the decrease in platelet counts seen following CRRT initiation in the majority of patients. A prospective study in this population is needed to optimize patient outcomes.