Elevated Serum Sodium and Tonicity Linked to Increased Hypertension and Heart Failure Risk

Overview

This large retrospective study of over 400,000 healthy adults found that serum sodium levels at the higher end of the normal range (≥140 mmol/L) and elevated tonicity are associated with significantly increased risks of developing hypertension and heart failure. These findings suggest that hydration-related markers can serve as early risk indicators in general healthcare settings.

Background

Ageing populations face a growing burden of chronic diseases, with hypertension and heart failure being major contributors to morbidity. Optimal hydration has emerged as a potential modifiable factor to reduce chronic disease risk. Serum sodium and tonicity, markers of hydration status, have been linked in prior studies to cardiovascular outcomes, but evidence from routine clinical data has been limited. This study leverages 20 years of electronic medical records from Israel’s Leumit Healthcare Services to evaluate these associations in a large, generally healthy population.

Data Highlights

Key Findings

• Serum sodium levels ≥140 mmol/L, though within normal limits, are associated with increased risk of hypertension and heart failure.
• Individuals with serum sodium ≥143 mmol/L have a 29% higher risk of hypertension and 20% higher risk of heart failure.
• Tonicity levels above 287 mosmol/kg similarly correlate with increased risks: 19% for hypertension and 15% for heart failure.
• Approximately 19% of healthy individuals had serum sodium in the 143–146 mmol/L range, and 39% in the 140–142 mmol/L range, indicating a substantial at-risk population.
• These hydration-related markers can be easily obtained from routine blood tests, facilitating early identification of individuals at risk.

Clinical Implications

Clinicians should consider serum sodium levels at the higher end of the normal range as potential indicators of increased cardiovascular risk. Evaluating patients’ hydration status and advising on fluid and salt intake may be beneficial preventive strategies. Routine monitoring of serum sodium and tonicity could help guide early interventions to reduce the incidence of hypertension and heart failure.

Conclusion

Elevated serum sodium and tonicity within the normal laboratory range are associated with increased long-term risks of hypertension and heart failure. These findings support the use of hydration markers in routine clinical practice to identify and manage individuals at elevated cardiovascular risk.

References

1. Leumit Healthcare Services Study, 2024 -- Association of Elevated Serum Sodium and Tonicity with Hypertension and Heart Failure