The RENAL Substudy of POLAR

ANZICS CTG Endorsed Study

The RENAL Substudy of POLAR

Study Description

Hypothermia has been shown to provide a protective effect after renal injury in animal models. However, there has been little clinical investigation of the renal effects of hypothermia. Taking advantage of the opportunity offered by the POLAR multicentre randomised controlled trial of hypothermia in traumatic brain injury (TBI), this substudy has investigated whether in patients with TBI: a) early and sustained hypothermia reduced the severity, incidence and duration of Acute Kidney Injury (AKI); b) the release of biomarkers of kidney injury including NGAL is reduced by cooling compared to maintenance of normothermia; c) the release of biomarkers of kidney injury including NGAL predicted the severity, occurrence and duration of AKI in patients with TBI. This study provided a unique opportunity to evaluate the benefit of early and sustained hypothermia as a treatment for AKI and may provide insight into the mechanisms of action of hypothermia in AKI. Study of the biomarkers will provide insight into their release and performance as markers of AKI and their response to therapy.

Management Committee

Elizabeth Moore (Chair / Project Manager), Michael Bailey, Rinaldo Bellomo, and Alistair Nichol.

Administering Institution

ANZIC Research Centre, Monash University


Robert Atkins

Sample Size

500 patients – POLAR-AKI; 53 patients – POLAR-Biomarkers.


Intensive Care Foundation (joint funding for EPO-TBI and POLAR renal substudies) $13,553.


ACTRN12609000764235 (POLAR Study)


Elizabeth Moore (email)