Biomarkers for sepsis and the role of automated haematology systems

The identification of novel biomarkers for the prediction and/or early diagnosis of sepsis is crucial. Markers such as interleukin-6 (IL-6), C-reactive protein (CRP) and lipopolysaccharide binding protein (LBP) have been proposed for diagnosing or monitoring sepsis.^1,2 The latter two biomarkers also increase in patients with inflammation due to trauma or surgery, and therefore their diagnostic relevance in critically ill patients with sepsis is far from perfect.³ Procalcitonin tests also show promise but there is currently insufficient evidence to recommend their routine adoption in the NHS.⁴

The Surviving Sepsis Campaign recommends that the first essential step is to identify suspected infection.⁵ There also needs to be a differential diagnosis between sepsis and non-infectious systemic inflammatory response syndrome (SIRS), The full blood count (FBC) and coagulation screen are among the first laboratory tests available to clinicians and therefore changes in parameters could provide potential biomarkers for infection and sepsis. The Sysmex range of analysers has unique parameters and graphical displays that can be of value to laboratory staff looking for signs of sepsis in samples from accident and emergency (A&E) or the intensive care unit (ICU).

Elevation in the white blood count (WBC) is considered to be too non-specific to be of use in sepsis detection,⁶ but changes in WBC subpopulations could be of greater interest. In particular, circulating neutrophils and monocytes are among the first cells to respond to pathogenic organisms.