Lactate-to-Albumin Ratio for Predicting Post-Contrast Acute Kidney Injury After Contrast-Enhanced CT in the Emergency Department.

OBJECTIVE

To evaluate the association between the lactate-to-albumin ratio (LAR) and the development of post-contrast acute kidney injury (PC-AKI) in patients undergoing intravenous contrast-enhanced computed tomography (CT) in the emergency department (ED), and to compare its discriminative performance with other biomarker ratios.

METHODS

This retrospective observational study included adult patients who underwent contrastenhanced CT in a tertiary ED between January 2022 and January 2025. Patients with available baseline and 48-72-hour post-contrast serum creatinine measurements were analyzed. LAR, blood urea nitrogen-to-albumin ratio (BAR), C-reactive protein-to-albumin ratio (CAR), and neutrophil-tolymphocyte ratio (NLR) were calculated using laboratory values obtained at ED presentation. Logistic regression analyses were performed, and receiver operating characteristic curves were constructed.

RESULTS

A total of 695 patients were included, and PC-AKI occurred in 43 (6.2%). Patients with PCAKI were older and had higher hemoglobin, creatinine, blood urea nitrogen, C-reactive protein, and lactate levels, as well as lower albumin and estimated glomerular filtration rate values (all p<0.05). LAR, BAR, CAR, and NLR differed between groups. In multivariable analysis, LAR (OR=3.898; 95% CI: 2.799-5.430; p<0.001), BAR (OR=1.635; 95% CI: 1.171-2.283; p=0.004), and NLR (OR=1.820; 95% CI: 1.359-2.438; p<0.001) were associated with PC-AKI. LAR showed an area under the curve of 0.854, with a sensitivity of 88.4% and a negative predictive value of 98.9% at a cut-off of >0.51.

CONCLUSION

LAR measured at ED presentation was associated with the development of PC-AKI following contrast-enhanced CT and demonstrated higher discriminative performance compared with other evaluated ratios. These findings suggest that LAR may be useful for risk stratification in this clinical context.