# Impact of Nephrology Consultation on Moderate and Severe Hyponatremia Outcomes and Length of Hospital Stay

## TL;DR

This study found that early nephrology consultation for hospitalized patients with moderate to severe low sodium levels was linked to longer hospital stays but did not improve survival or reduce readmissions.

## Contribution

The study is one of the first to evaluate the impact of nephrology consultation timing on outcomes in hospitalized hyponatremic patients.

## Key findings

- Early nephrology consultation was associated with a longer hospital stay (median 7-8 days) compared to 5 days without consultation.
- No significant differences in mortality, sodium correction rates, or readmission rates were observed across consultation groups.
- No cases of osmotic demyelination syndrome were observed in any group.

## Abstract

Background

Hyponatremia is a frequent electrolyte disorder among hospitalized patients, associated with increased morbidity, mortality, and healthcare costs. Timely nephrology consultation may influence patient outcomes, but its impact remains unclear.

Objective

To evaluate the association of early versus late or no nephrology consultation on clinical outcomes, including mortality, length of stay, sodium correction rates, and readmission among hospitalized patients with moderate to severe hyponatremia.

Methods

We conducted a retrospective cohort study of 423 adult patients admitted with serum sodium <130 mmol/L at New York-Presbyterian Queens from July 2023 to June 2024. Patients were categorized into early consultation (≤48 hours), late consultation (>48 hours), or no nephrology consultation groups. Primary outcomes included inpatient, 30-day, and 90-day mortality, and length of hospital stay. Secondary outcomes comprised readmission rates, discharge disposition, recurrence of hyponatremia, and neurological complications, including osmotic demyelination syndrome. Multivariable regression adjusted for confounders such as age, comorbidities, and admission unit.

Results

Early nephrology consultation was provided to 41% of patients, late consultation to 20%, and 39% received no consultation. Mortality rates did not differ significantly among groups at any time point. Nephrology consultation was associated with a longer hospital stay (median 7-8 days vs. 5 days; p<0.001) but did not significantly affect sodium correction rates or readmission. No cases of osmotic demyelination syndrome were observed. Causes of death were predominantly cancer, infection, and cardiorespiratory events. Multivariable analysis confirmed no significant mortality difference attributable to consultation timing but a significant increase in length of stay with nephrology involvement.

Conclusion

In patients with moderate to severe hyponatremia, nephrology consultation was associated with longer hospitalization but did not significantly alter mortality or readmission rates. Further prospective studies are needed to clarify the role of nephrology input in optimizing outcomes and resource utilization in hyponatremic patients.