From the FDA Drug Label
Thereafter, patients could resume or initiate fluid restriction (defined as daily fluid intake of ≤1. 0 liter/day) as clinically indicated. The recommended water restriction for a patient with hyponatremia (sodium level of 129 mEq/L) is ≤1.0 liter/day, as clinically indicated 1.
- This restriction is defined as daily fluid intake and may be initiated or resumed after the first 24 hours of therapy.
From the Research
For a sodium level of 129 mEq/L, which indicates mild hyponatremia, I recommend a fluid restriction of 1-1.5 liters per day. This means limiting your total daily fluid intake from all sources, including water, beverages, soups, and foods with high water content. Start by tracking all fluids consumed and spreading this allowance throughout the day. Prioritize small sips rather than large volumes at once. This restriction helps your body correct the sodium imbalance by preventing further dilution of sodium in your bloodstream. Hyponatremia occurs when there's too much water relative to sodium in your body, and restricting fluids allows your kidneys to excrete excess water while retaining sodium.
Key Considerations
- Monitor for symptoms like headache, confusion, or muscle cramps, which could indicate worsening hyponatremia.
- The fluid restriction should continue until your sodium levels normalize (typically above 135 mEq/L), as determined by follow-up blood tests.
- Consult with your healthcare provider about the exact duration of restriction and for any adjustments based on your specific medical conditions. According to the most recent and highest quality study 2, the mainstay of treatment for patients with SIADH is fluid restriction, and for acute or severely symptomatic hyponatremia, hypertonic saline should be used. Additionally, the study 3 highlights the importance of limiting the correction of serum sodium to ≤10 mEq/L in 24 hours to prevent osmotic demyelination syndrome. However, for patients with severe hyponatremia and high-risk features, especially those with serum sodium <115 mEq/L, it is recommended to limit serum sodium correction to <8 mEq/L 3.
Additional Recommendations
- Patients with severe hyponatremia and symptoms of altered mental state or seizures should be admitted to hospital for monitoring of fluid restriction and consideration of hypertonic saline 4.
- Thiamine supplementation is advisable for any patient with hyponatremia whose dietary intake has been poor 3.
- Serum sodium should be monitored in patients with primary polydipsia when commencing or adjusting psychotropic medications 5.