Association Between AKI and Hyponatremia in Critically Ill Children

A new study from the Division of Pediatric Nephrology at UPMC Children's Hospital of Pittsburgh has uncovered strong evidence for an association between hyponatremia and acute kidney injury in children admitted to the intensive care unit. 

The study was published in February 2022 in the journal Pediatric Nephrology. Cassandra Formeck, MD, MS, was the study’s lead author, and Division clinical director, Michael L. Moritz, MD, was the senior author.

Dr. Formeck and colleagues' study was a single-center retrospective analysis of critically ill children admitted to intensive care units at UPMC Children's between 2010 and 2014.

The team analyzed data from 5,057 cases of pediatric critical illness to characterize the frequency of hyponatremia and its association with the development of a new AKI or a progression from no or stage 1 AKI to severe stage 2 or 3 AKI after admission to the ICU.

“While there is some evidence in adult populations linking hyponatremia with AKI in critical illness, our study is the first to examine this in a pediatric population,” says Dr. Formeck.

Within the study cohort, 13.3% of individuals presented to the ICU with varying levels of hyponatremia. Within the hyponatremic subset, 9.2% of individuals developed new or severe progression of AKI while admitted to the ICU. Individuals presenting to the ICU with hyponatremia were found to have a 75% greater risk of acquiring a severe AKI when compared to individuals with normal sodium levels at the time of admission.

Further analysis also found that hyponatremic individuals who developed a severe AKI after admission required longer lengths of stay in the ICU, had a higher rate of need for kidney replacement therapy, and had higher rates of having acute kidney disease or AKI when discharged from the hospital. Mortality rates were also higher for this cohort, though the total incidence of hospital mortality was low.

Dr. Formeck and colleagues’ analysis also uncovered an increase in the risk of developing a severe AKI related to lower sodium levels. For every decrease by 1 mEq/L, there was a corresponding 0.05% increase in risk.

“While more research is required to further explore the mechanisms at play in AKI development in critically ill children who are hyponatremic, our study shows a strong association between the two. Pediatric nephrologists and critical care specialists should keep this data in mind and routinely assess and monitor critically ill patients upon presentation and the early days after admission,” says Dr. Formeck. “Preventing the development of AKI is of paramount concern in this patient population, and knowing that hyponatremia is a significant risk factor gives clinicians another marker by which patients can be triaged."

Learn more about Dr. Formeck and the Division of Pediatric Nephrology at UPMC Children’s Hospital of Pittsburgh.

Reference

Formeck CL, Siripon N, Joyce EL, Ayus JC, Kellum JA, Moritz ML. Association of Early Hyponatremia and the Development of Acute Kidney Injury in Critically Ill Children. Pediatr Nephrol. 2022 Feb 24. Online ahead of print.