From the Guidelines
Treatment of hyponatremia in SIADH involves correcting the underlying water imbalance. The primary treatment option is free water restriction, which is recommended as a first-line treatment for asymptomatic mild SIADH and as an adjunct to other therapy for severe cases, with a restriction of less than 1 L/d 1.
- For severe hyponatremia, hypertonic 3% saline IV may be administered in life-threatening or acute symptomatic cases, particularly when serum sodium levels are below 120 mEq/L 1.
- Additional treatment options include demeclocycline, lithium, and vasopressin 2 receptor antagonists such as conivaptan, lixivaptan, tolvaptan, and satavaptan, which may be used to correct hyponatremia, especially in cases where fluid restriction is not sufficient or effective 1.
- It is essential to assess the effective arterial blood volume and exclude other causes of hyponatremia, such as hypoadrenalism, hypothyroidism, and renal salt wasting, to ensure accurate diagnosis and treatment of SIADH 1.
- The treatment approach should be based on the severity of hyponatremia and the presence of symptoms, with more aggressive treatment reserved for severe cases with acute neurological symptoms 1.
From the Research
Treatment Options for Hyponatremia in SIADH
The treatment options for hyponatremia in Syndrome of Inappropriate Antidiuretic Hormone (SIADH) secretion include:
- Fluid restriction: This is the mainstay of treatment for chronic SIADH, with a restriction of 800-1200 mL/24 hours 2
- Hypertonic saline: This is used in the initial treatment of symptomatic SIADH with severe neurological deficits, with a goal of correcting hyponatremia slowly (<10-12 mmol/l within the first 24 h, and <18 mmol/l within the first 48 h) 3, 2
- Demeclocycline: This can be used to induce a negative free-water balance in patients who cannot tolerate fluid restriction 4, 3
- Vasopressin receptor antagonists (vaptans): These have been shown to be efficacious in the treatment of SIADH, with an acceptable safety profile 3, 5
- Urea, lithium, phenytoin, and loop diuretics: These have been reported to be effective in the treatment of SIADH, but there are few data to support their use 4
- Furosemide: This can be used in combination with hypertonic saline to produce a negative free-water balance 4, 6
- Tolvaptan: This is a vasopressin receptor antagonist that can be used to achieve eunatremia in patients with SIADH 6
Considerations for Treatment
When treating hyponatremia in SIADH, it is important to:
- Limit the daily increase of serum sodium to less than 8-10 mmol/liter to avoid osmotic demyelination 5
- Monitor serum sodium levels closely, especially in the first 24-48 hours of treatment 5
- Avoid overcorrection of serum sodium levels, which can lead to osmotic demyelination 3, 6
- Consider the use of algorithms to guide treatment, such as those developed by a multidisciplinary Spanish group 6