Relationship between early serum sodium and potassium levels and AKI severity and prognosis in oliguric AKI patients.

PURPOSE Acute kidney injury (AKI) is a common organ dysfunction in ICU and up to now there is no good way to predict the AKI progression and patient prognosis. Blood electrolyte tests are common in ICU, but there are few studies on early blood electrolytes and the AKI progression and patient prognosis. Therefore, we concentrated on the serum sodium and potassium levels before AKI diagnosis and evaluated the relationship between serum sodium and potassium levels and the severity and prognosis of AKI. METHODS This study included data of all patients from the MIMIC-III. We used the urine output criteria in the KDIGO as diagnostic criteria for oliguric AKI. Patients admitted to the ICU several times only included their initial ICU admission results. Patients younger than 18 years old, diagnosed with AKI stage 3, ICU stays less than 24 h or without corresponding laboratory results or data were excluded. The included patients were divided into four groups based on the interquartile range of serum sodium and potassium. We evaluated the serum sodium and potassium levels before AKI diagnosis and AKI severity and prognosis through retrospective analysis. RESULTS Patients with serum potassium > 4.6 mmol/L were more likely to progress to AKI stage 3 or death than patients with serum potassium ≤ 4.6 mmol/L (overall p   141 mmol/L had a higher risk of progressing to AKI stage 3 (overall p = 0.00023) and risk of death (overall p < 0.0001) than other patients. In the Cox regression model, after adjusting for age, sex, and BMI, serum sodium or potassium were associated with AKI progression and prognosis (p < 0.01). After continuing to adjust for comorbidities, serum potassium was still associated with AKI progression and prognosis (p < 0.01), but serum sodium was only associated with prognosis (p = 0.027). After adjusting for other indicators, there was no statistically significant correlation between serum sodium or potassium and AKI progression and prognosis. After adjusting for serum sodium or potassium, the corresponding results were not significantly different from those before adjustment. CONCLUSION This study found that abnormal serum sodium or potassium levels before AKI diagnosis were more likely to lead to AKI progression and poor prognosis, of which lower serum sodium and higher serum potassium were more likely to progress to AKI stage 3 or death.