From the Guidelines
Hyponatremia symptoms include headache, nausea, vomiting, confusion, fatigue, irritability, muscle weakness, cramps, and seizures in severe cases, and prompt treatment is essential to prevent serious complications, especially in patients with severe symptoms such as life-threatening manifestations, cardio-respiratory distress, abnormal and deep somnolence, seizures, and coma 1.
Symptoms of Hyponatremia
The symptoms of hyponatremia can be subtle and nonspecific, resembling general malaise or flu-like symptoms, but as sodium levels drop further, neurological symptoms become more prominent due to brain cell swelling caused by water moving into cells.
- Early symptoms: headache, nausea, vomiting, confusion, fatigue, irritability, muscle weakness, cramps
- Severe symptoms: seizures, coma, potentially death if left untreated
- Severity of symptoms: correlates with both the absolute sodium level and how quickly it developed, with rapid drops causing more dramatic symptoms than gradual decreases
Patient Presentation
Elderly patients may present with falls or altered mental status, while athletes might experience exercise-associated hyponatremia with symptoms appearing during or after prolonged exertion.
- Anyone experiencing these symptoms, especially after situations that might affect fluid balance (excessive water intake, intense exercise, certain medications, or medical conditions), should seek immediate medical attention
Treatment Considerations
Treatment of hyponatremia should be initiated when serum sodium is lower than 130 mmol/L, although there is no good evidence regarding the level of serum sodium at which treatment should be initiated 1.
- Hypovolemic hyponatremia: requires plasma volume expansion with saline solution and the correction of the causative factor
- Hypervolemic hyponatremia: requires attainment of a negative water balance, and non-osmotic fluid restriction may be helpful in preventing a further decrease in serum sodium levels
- Hypertonic sodium chloride administration: may be considered in patients with severe hyponatremia who are expected to get a liver transplant within a few days, but should be limited to severely symptomatic hyponatremia due to the risk of central pontine myelinolysis 1.
From the FDA Drug Label
The usual starting dose for tolvaptan tablets is 15 mg administered once daily without regard to meals. Increase the dose to 30 mg once daily, after at least 24 hours, to a maximum of 60 mg once daily, as needed to achieve the desired level of serum sodium. Patients should be in a hospital for initiation and re-initiation of therapy to evaluate the therapeutic response and because too rapid correction of hyponatremia can cause osmotic demyelination resulting in dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma and death
- Hyponatremia symptoms that can be exacerbated by too rapid correction include:
- Dysarthria
- Mutism
- Dysphagia
- Lethargy
- Affective changes
- Spastic quadriparesis
- Seizures
- Coma
- Death 2
From the Research
Hyponatremia Symptoms
- Mild symptoms of hyponatremia include nausea, vomiting, weakness, headache, and mild neurocognitive deficits 3
- Severe symptoms of hyponatremia include delirium, confusion, impaired consciousness, ataxia, seizures, and, rarely, brain herniation and death 3
- Clinical manifestations of hyponatremia also include headache, dizziness, nausea/vomiting, seizures, obtundation, and death 4
- In acute and severe hyponatremia, dramatic symptoms, such as seizures, acute psychosis, permanent brain damage, brain-stem herniation, leading to coma and death may occur 5
- In chronic hyponatremia, symptoms are generally less dramatic and may include headache, nausea, vomiting, gait alterations, muscle cramps, restlessness, and disorientation 5
Classification of Hyponatremia
- Hyponatremia is considered mild when the sodium concentration is 130 to 134 mEq per L, moderate when 125 to 129 mEq per L, and severe when less than 125 mEq per L 3
- Hyponatremia can be classified as hypovolemic, euvolemic, or hypervolemic, and management is based on the underlying cause and severity of symptoms 3
Treatment and Management
- Treatment decisions are based on the underlying cause and severity of symptoms 4
- Patients with a sodium concentration of less than 125 mEq per L and severe symptoms require emergency infusions with 3% hypertonic saline 3
- Hypovolemic hyponatremia is treated with normal saline infusions, while euvolemic hyponatremia includes restricting free water consumption or using salt tablets or intravenous vaptans 3
- Hypervolemic hyponatremia is treated primarily by managing the underlying cause and free water restriction 3