The Development of Intensive Care Unit Acquired Hypernatremia Is Not Explained by Sodium Overload or Water Deficit: A Retrospective Cohort Study on Water Balance and Sodium Handling

Background. ICU acquired hypernatremia (IAH, serum sodium concentration (sNa) >= 143 mmol/L) is mainly considered iatrogenic, induced by sodium overload and water deficit. Main goal of the current paper was to answer the following questions: Can the development of IAH indeed be explained by sodium intake and water balance? Or can it be explained by renal cation excretion? Methods. Two retrospective studies were conducted: a balance study in 97 ICU patients with and without IAH and a survey on renal cation excretion in 115 patients with IAH. Results. Sodium intake within the first 48 hours of ICU admission was 12.5 [9.3-17.5] g in patients without IAH (n = 50) and 15.8 [9-21.9] g in patients with IAH (n = 47), p = 0.13. Fluid balance was 2.3 [1-3.7] L and 2.5 [0.8-4.2] L, respectively, p = 0.77. Urine cation excretion (urine Na + K) was