Acute kidney injury (AKI) is a common complication in septic patients, imposing a heavy burden of illness in terms of morbidity and mortality. Serum lactate is a widely used marker predicting the severity of sepsis. A paucity of research has investigated septic AKI in emergency departments (EDs) and its correlation with initial serum lactate level. This study aimed at identifying risk factors for septic AKI and clarifying the link between initial serum lactate level and septic AKI in ED patients.

A retrospective cohort study was conducted at a single tertiary referral medical center. The medical records of all adult ED patients with measurement of serum lactate and creatinine between January 2012 and December 2016 were reviewed. A total of 696 septic patients were stratified into AKI and non-AKI groups according to Acute Kidney Injury Network (AKIN) criteria for further statistical analysis.

Ninety-nine septic patients (14.2%) had AKI, with AKIN-I, AKIN-II, and AKIN-III in 71.7%, 11.1%, and 17.2% of patients, respectively. Compared with the non-AKI group, the AKI group had a significantly higher mortality rate (71.7% vs. 21.3%, p < 0.001). Independent risk factors for septic AKI included liver disease (adjusted odds ratio [AOR] = 2.02, 95% confidence interval [CI] = 1.16–3.52), diabetes mellitus (AOR = 1.73, 95% CI = 1.11–2.69), chronic kidney disease (AOR = 1.68, 95% CI = 1.06–2.66), and initial serum lactate (AOR = 1.08, 95% CI = 1.02–1.14).

Patients with septic AKI had an overwhelmingly higher mortality rate. The comorbidities of liver disease, diabetes mellitus, and chronic kidney disease were correlated with septic AKI and in combination with an elevated initial serum lactate level had predictive regarding AKI and further mortality in ED septic patients.