Acute kidney injury with hypernatremia and major adverse kidney events

Abstract

Introduction. Consequences of hypernatremia in akute kidney injury (AKI-hyperNa) is poorly understood. We analyzed the risk of major adverse kidney events (MAKE) in comparison with AKI and normal serum sodium (AKI-normalNa). Such data could help in understanding this complex interaction. Methods. In this retrospective cohort we compared the AKI-hyperNa with the AKI-normalNa regarding the risk of MAKE, which include death, new dialysis requirement, and worsening kidney function (≥25% decrease in estimated glomerular filtration rate), at 10 (MAKE10) and at 30–90 days (MAKE30–90) using multivariate logistic regression and area under the curve (AUC) analysis. The association between serum sodium levels (per 1 mEq/l increase) and the number of days with hypernatremia was also compared. Results. A total of 357 patients were included (78 with AKI-hyperNa and 279 with AKI-normalNa). Compared to the AKI-normalNa, AKI-hyperNa were predominantly male (73% versus 59%), experienced hypernatremia for a longer duration (3 days versus 0 days), and took 5 days to normalize serum sodium levels. After multivariate regression analysis, the AKI-hyperNa group had higher risk of MAKE10 [odds ratio (OR) 5.7, confidence interval (CI) 2.5 to 12.89, p < 0.001] with an AUC of 0.79. Also its components such as mortality and decreased estimated glomerular filtration rate (OR 2.13, CI 1.11 to 4.07, p = 0.021 and OR 20.14, CI 7.69 to 10.03, p = 0.001, respectively). A similar trend was found for MAKE30–90 (OR 4.17, CI 1.73 to 10.03, p ≤ 0.001). A gradual increase in serum sodium was associated with a higher risk of MAKE (OR 1.07, CI 1.04 to 1.11, p ≤ 0.001), as was the number of days spend with hypernatremia (OR 1.51, CI 1.22 to 1.87, p = 0.001). Conclusions. In this cohort, AKI-hyperNa compared with AKI-normalNa had a fivefold risk of short- and long-term MAKE. This event was more frequently observed as serum sodium increased and it was closely related to the number of days that hypernatremia persisted.