Hyperlactatemia at initiation of continuous renal replacement therapy (CRRT) and reduced lactate clearance may indicate high death risk in ICU patients with acute kidney injury (AKI), investigators report.

“Monitoring serum lactate may be needed to precisely predict worse outcomes,” according to Seung Seok Han, MD, PhD, of Seoul National University College of Medicine in Korea, and colleagues.

The investigators retrospectively reviewed data from 1661 adults who underwent CRRT due to AKI at Seoul National University Hospital from June 2010 to December 2020. Septic AKI occurred in 58.6%. Of the cohort, 19.1%, 48.3%, and 32.6% of patients had low (2 mmol/L or less), moderate (2.1-7.5 mmol/L), and high (7.6 mmol/L or more) lactate levels, respectively, at CRRT initiation.

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Compared with the low-lactate group, the moderate- and high-lactate groups had a significant 1.6- and 4.2-fold increased risk of in-hospital mortality, a significant 1.6- and 4.2-fold increased risk of ICU mortality, and a significant 1.5- and 4.5-fold increased risk of mortality while on CRRT, respectively, Dr Han and colleagues reported in BMC Nephrology.

The Sequential Organ Failure Assessment (SOFA) and the Acute Physiology and Chronic Health Evaluation (APACHE) II score have been shown to correlate with outcomes of patients who undergo CRRT. Adding lactate levels into severity index-based models improved prediction of death. The lactate-enhanced models had higher area under the receiver operating curves than the models without lactate values (0.764 vs 0.702 for SOFA score and 0.737 vs 0.678 for APACHE II score).

“Our result demonstrates that an early trend in serum lactate remains a reliable marker for risk-stratification regardless of the effect of CRRT,” Dr Han’s team stated. The causes of hyperlactatemia were unknown, limiting further analysis of mortality risk.


Kim SG, Lee J, Yun D, et al. Hyperlactatemia is a predictor of mortality in patients undergoing continuous renal replacement therapy for acute kidney injury. BMC Nephrol. 24(1):11. doi:10.1186/s12882-023-03063-y