Increased Serum Sodium at Acute Kidney Injury Onset Predicts In-Hospital Death

Abstract

Background: Over the last decades, acute kidney injury (AKI) has been identified as a potentially fatal diagnosis which substantially increases in-hospital mortality in the short term and morbidity/mortality in the long term. However, reliable biomarkers for predicting AKI-associated outcomes are still missing. In this study, we assessed whether serum sodium, measured at different time points during the in-hospital treatment period, provided prognostic information in AKI.Methods: This was a retrospective, observational cohort study. AKI subjects were identified via the in-hospital AKI alert system. Serum sodium and potassium levels were documented at five pre-defined time points: hospital admission, AKI onset, minimum estimated glomerular filtration rate, minimum and maximum of the respective electrolyte during the treatment period. In-hospital death, the need for kidney replacement therapy (KRT) and recovery of kidney function were defined as endpoints.Results: Patients who suffered in-hospital death (n = 37, 23.1%) showed significantly higher serum sodium levels at diagnosis of AKI (survivors: 145.7 ± 2.13 vs. non-survivors: 138.8 ± 0.636 mmol/L, P = 0.003). A logistic regression model was significant for serum sodium levels in patients with in-hospital death (X 2 , P = 0.003; odds ratio = 1.08 (1.022 -1.141); R 2 = 0.082; d = 0.089). This suggests an increase of the relative risk for in-hospital death by 8% with every unit of serum sodium increase. Patients with a sodium above the upper normal range at AKI diagnosis were also more likely to suffer in-hospital death (P = 0.001). Conclusion:In summary, we present evidence that serum sodium, measured at time of AKI diagnosis, potentially serves as a predictor for in-hospital death in patients with AKI.

Hypernatremia: Epidemiology and Predictive Role in Emerging and Established Acute Kidney Injury

“…In a recent study conducted by our group [ 39 ], de novo AKI was detected using an in-hospital AKI alert system. This system automatically notifies the responsible nephrologist if either criterion 1 or 2 of the Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guidelines for AKI [ 40 ] is met.…”

“…Although the study was designed retrospectively, it demonstrated the significant prognostic value of serum sodium in predicting outcomes in emerging AKI. Table 2 [6,34,[36][37][38][39][40] provides a summary of studies investigating the risk prediction of hypernatremia in AKI.…”

“…Peres et al, 2015 [36] Retrospective, single-center analysis, ICU, n = 152 AKI onset and ICU mortality Hypernatremia predicted ICU death but not AKI Mendes et al, 2015 [37] Secondary analysis of 772 individuals from a 2011 published prospective trial [38] In-hospital mortality Highest mortality in subjects with hypernatremia and AKI, hypernatremia independently mortality-predictive Woitok et al, 2020 [6] Retrospective cross-sectional study in emergency department patients Death in AKI patients Hypo-and hypernatremia death predictive Marahrens et al, 2023 [39] Retrospective, observational, inclusion of patients with de novo AKI, serum sodium analysis at five pre-defined timepoints Need of KRT, in-hospital death Increase of the relative risk of in-hospital death by 8% with every unit of serum sodium increase ICU: intensive care unit; AKI: acute kidney injury; KRT: kidney replacement therapy; KDIGO: Kidney Disease: Improving Global Outcomes.…”