Association of early hyponatremia and the development of acute kidney injury in critically ill children

Abstract

Background: Hyponatremia is an independent prognostic factor for mortality; however, the reason for this remains unclear. An observed relationship between hyponatremia and the development of acute kidney injury (AKI) has been reported in certain disease states, but hyponatremia has not been evaluated as a predictor of AKI in critically ill patients or children.

Methods: This is a single-center retrospective cohort study of critically ill children admitted to a tertiary care center. We performed regression analysis to assess the association between hyponatremia at ICU admission and the development of new or worsening stage 2 or 3 (severe) AKI on days 2-3 following ICU admission.

Results: Among the 5057 children included in the study, early hyponatremia was present in 13.3% of children. Severe AKI occurred in 9.2% of children with hyponatremia compared to 4.5% of children with normonatremia. Following covariate adjustment, hyponatremia at ICU admission was associated with a 75% increase in the odds of developing severe AKI when compared to critically ill children with normonatremia (aOR 1.75, 95% CI 1.28-2.39). Evaluating sodium levels continuously, for every 1 mEq/L decrease in serum sodium level, there was a 0.05% increase in the odds of developing severe AKI (aOR 1.05, 95% CI 1.02-1.08). Hyponatremic children who developed severe AKI had a higher frequency of kidney replacement therapy, AKI or acute kidney disease at hospital discharge, and hospital mortality when compared to those without.

Conclusions: Hyponatremia at ICU admission is associated with the development of new or worsening AKI in critically ill children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Keywords: Acute kidney injury; Critical care outcomes; Hyponatremia; Pediatric; Pediatric intensive care unit.

Fig. 1

Flow diagram of study cohort with exclusions. AKI, acute kidney injury; CKD, chronic kidney disease; ICU, intensive care unit. ^aMeasured within 6 h prior to or after ICU admission. ^bMeasured within 24 h of ICU admission

Fig. 2

Adjusted probability of developing stage 2 or 3 AKI among critically ill children by sodium level at ICU admission. AKI, acute kidney injury; ICU, intensive care unit

Fig. 3

Secondary outcomes among critically ill children by primary exposure and primary outcome status. AKI, acute kidney injury; AKD, acute kidney disease; ICU, intensive care unit; KRT, kidney replacement therapy