Heparin-binding protein as a biomarker of acute kidney injury in critical illness

Background: There is no biomarker with high sensitivity and specificity for the development of acute kidney injury (AKI) in a mixed intensive care unit (ICU) population. Heparin-binding protein (HBP) is released from granulocytes and causes increased vascular permeability which plays a role in the development of AKI in sepsis and ischemia. The aim of this study was to investigate whether plasma levels of HBP on admission can predict the development of AKI in a mixed ICU population and in the subgroup with sepsis. Methods: Longitudinal observational study with plasma HBP levels from 245 patients taken on admission to ICU. Presence and severity of AKI was scored daily for 1 week. Results: Mean (95% CI) plasma concentrations of log HBP (ng/ml) in the groups developing different stages of AKI were: stage 0 (n = 175), 3.5 (3.4–3.7); stage 1 (n = 33), 3.7 (3.5–4.0), stage 2 (n = 20), 4.4 (3.5–4.8); and stage 3 (n = 17), 4.6 (3.8–5.2). HBP levels were significantly higher in patients developing AKI stage 3 (P < 0.01) compared to AKI stage 0 and 1. The area under the curve (AUC) for HBP to discriminate the group developing AKI stage 2–3 was 0.70 (CI: 0.58–0.82) and in the subgroup with severe sepsis 0.88 (CI: 0.77–0.99). Conclusion: Heparin-binding protein levels on admission to ICU are associated with the development of severe kidney injury. The relationship between HBP and AKI needs to be further validated in larger studies.