Serum potassium trajectory during AKI and mortality risk

Background: Kidneys play a primary role in potassium homeostasis. The association between potassium (sK + ) level and mortality or the need for kidney replacement therapy (KRT) during acute kidney injury (AKI) has not been adequately explored. Methods: In this prospective cohort study, AKI patients admitted to the Hospital Civil de Guadalajara were enrolled from August 2017 to June 2021 with AKI. We divided patients into 8 groups based on the serum potassium level trajectories up to ten days following hospitalization, (1) normokalemia (normoK), defined as sK + values between 3.5 and 5.5 mEq/L; (2) corrected hyperkalemia (hyperK), sK + > 5.5 mEq/L on hospital admission and decreased to normoK; (3) corrected hypokalemia (hypoK), sK + < 3.5 mEq/L on hospital admission and increased to normoK; (4) fluctuating potassium, sK + increased / decreased in and out of normoK parameters; (5) uncorrected hypoK, sK + < 3.5 mEq/L; (6) normoK to hypoK, sK + that were normal on hospital admission and decreased to hypoK and never went back to normal; (7) normoK to hyperK, sK + that were normal on hospital admission and increased to hyperK and never went back to normal; (8) uncorrected hyperK, sK + > 5.5 mEq/L. We assessed the association of serum potassium trajectories with mortality and the need for KRT (secondary objective). Results: : A total of 311 AKI patients were included. The mean age was 52.6 years, and 182 (58.6%) were male. AKI stage 3 was present in 199 (63.9%). KRT started in 112 (36%) patients, and 66 (21.2%) died. After adjusting for confounders, 10-day hospital mortality was significantly higher in group 7 and 8 (OR, 1.37 and 1.63, p = <0.05, for both, respectevely), and KRT initiation was higher only in group 8 (OR 1.40, p = < 0.05) compared with group 1. Mortality in different subgroups of patients in group 8 did not change the primary results. Conclusion: In our prospective cohort, most patients with AKI had alterations in sK + . NormoK to hyperK and Uncorrected hyperK were associated with death, while only uncorrected hyperK was correlated with the need for KRT.