From the Research
Normal Range for Serum Sodium Levels
The normal range for serum sodium levels is generally considered to be between 135-145 mmol/L 1. However, this range may vary depending on the population being studied and the method of measurement used 2.
Factors Affecting Serum Sodium Levels
Several factors can affect serum sodium levels, including:
- Age: Serum sodium levels may be lower in older adults 1
- Sex: No significant differences in serum sodium levels have been found between men and women 3
- Blood pressure: High serum sodium levels may be associated with elevated blood pressure 3
- Kidney function: High serum sodium levels may be associated with impaired kidney function, independently of blood pressure 3
Measurement of Serum Sodium Levels
Serum sodium levels can be measured using different methods, including indirect and direct ion-selective electrode (ISE) methods 2. The indirect ISE method may result in higher measurements than the direct ISE method, especially at higher sodium levels.
Clinical Significance of Serum Sodium Levels
Serum sodium levels outside of the normal range can have significant clinical implications. Hyponatremia (serum sodium < 135 mmol/L) can cause symptoms such as headaches, nausea, and vomiting, and can be life-threatening in severe cases 4, 5. Hypernatremia (serum sodium > 145 mmol/L) can also cause symptoms such as thirst, dark urine, and seizures, and can be associated with increased mortality 1.
Key Findings
- The normal range for serum sodium levels is between 135-145 mmol/L 1
- Serum sodium levels can be affected by age, blood pressure, and kidney function 1, 3
- Different measurement methods can result in different serum sodium levels 2
- Serum sodium levels outside of the normal range can have significant clinical implications 4, 5, 1