From the Guidelines
Mild hyponatremia typically presents with subtle symptoms that may be easily overlooked, including headache, nausea, fatigue, muscle cramps, and mild confusion, as noted in patients with serum sodium concentrations of 125 to 130 mEq/L 1.
Symptoms of Mild Hyponatremia
The symptoms of mild hyponatremia can vary but often include:
- Headache
- Nausea
- Fatigue
- Muscle cramps
- Mild confusion These symptoms occur because low sodium levels disrupt the osmotic balance between cells and their surrounding environment, causing water to move into cells, including brain cells, leading to cellular swelling.
Risk Factors and Considerations
Risk factors for hyponatremia include certain medications (particularly thiazide diuretics, SSRIs, and some antiepileptics), excessive water intake, heart failure, kidney disease, and endocrine disorders.
Management and Treatment
Treatment typically involves addressing the underlying cause and careful sodium correction, but should be guided by a healthcare provider to avoid correction that is too rapid 1. In cases of dilutional hyponatremia, fluid intake can be restricted to 1.0-1.5 L/day when the serum sodium concentration falls below 120-125 mmol/L 1. Administration of a plasma expander, such as albumin, may be considered for the treatment of hyponatremia 1. It's also important to note that hyponatremia should be treated 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. Hypertonic sodium chloride administration may improve natremia but enhances volume overload and worsens the amount of ascites and edema, and should be limited to severely symptomatic hyponatremia 1. In practice, after an initial rapid correction aimed at attenuating clinical symptoms, serum sodium concentration should not increase more than 8 mmol/L per day 1.
From the Research
Symptoms of Mild Hyponatremia
The symptoms of mild hyponatremia can be nonspecific and may include:
- Nausea
- Vomiting
- Weakness
- Headache
- Mild neurocognitive deficits 2
- Lack of concentration
- Forgetfulness
- Apathy
- Loss of balance 3
Severity of Symptoms
The severity of symptoms depends on the rapidity of development, duration, and severity of hyponatremia 4. Mild chronic hyponatremia is associated with cognitive impairment, gait disturbances, and increased rates of falls and fractures 4.
Diagnosis and Management
Mild hyponatremia is defined as a serum sodium concentration between 130-134 mmol/l 2, 3. The management of hyponatremia should consist of treating the underlying cause, and the approach may vary depending on the patient's fluid volume status (hypovolemic, euvolemic, or hypervolemic) 2, 4.
Treatment Options
Treatment options for hyponatremia include fluid restriction, urea, loop diuretics, demeclocycline, and vaptans 3, 5, 6. Vaptans, such as tolvaptan, have been shown to be effective in managing euvolemic and hypervolemic hyponatremia 5, 6. However, the risk of overcorrection should be carefully monitored to prevent osmotic demyelination syndrome 2, 4, 5.