CST3 and acute kidney injury: Within the limitations of this small cohort, our data suggest that elevated plasma endostatin may be an earlier and more specific signal of kidney stress or injury, especially in conjunction with clinical risk factors, than two previously proposed AKI markers: NGAL and cystatin C. Whether this signal is a useful tool to detect patients “at risk” of AKI, however, needs to be assessed in combination with validated clinical risk models in independent cohorts of critically ill patients.