Cheng-Hock Toh, M.D., of the University of Liverpool, United Kingdom, and colleagues examined the association between circulating histones and thrombocytopenia in patients in the intensive care unit. Histones are proteins associated with DNA; thrombocytopenia a blood disease characterized by an abnormally low number of platelets in the blood. The study appears in JAMA, which is being released to coincide with the Society of Critical Care Medicine’s 45th Critical Care Congress.
Thrombocytopenia is observed in approximately 30 percent to 40 percent of patients in the intensive care unit (ICU) and associated with poor outcomes. Histones induce profound thrombocytopenia in mice and are associated with organ injury when released following extensive cell damage in patients who are critically ill. This study included 56 patients with thrombocytopenia and 56 controls with normal platelet counts who were admitted to the ICU at Royal Liverpool University Hospital between June 2013 and January 2014.
The researchers found that histones circulated in the majority of thrombocytopenic patients and the histone levels were 2.5- to 5.5-fold higher than in nonthrombocytopenic controls. There was a significant association between high levels of histones at admission and subsequent decline in platelet counts among thrombocytopenic patients. High admission histone levels were associated with moderate to severe thrombocytopenia and development of clinically important thrombocytopenia.
“Circulating histones are potential markers of disease severity, and the association with thrombocytopenia may reflect this. Nevertheless, the novel associations reported in this study extend previous reports demonstrating profound thrombocytopenia following histone infusion into mice and suggest that, if confirmed, circulating histones may be valuable in predicting or monitoring thrombocytopenia in patients who are critically ill,” the authors write.