How to approach a 78-year-old patient with hyponatremia (low sodium levels) according to National Institute for Health and Care Excellence (NICE) guidance?

From the Guidelines

For a 78-year-old with hyponatremia, the approach should prioritize assessing the severity and symptoms, and then determining the underlying cause by assessing volume status and measuring urine osmolality and sodium, as the most recent guideline from 2022 suggests that improvement in hyponatremia can improve clinical outcomes 1. The first step is to determine if the hyponatremia is acute (developing in less than 48 hours) or chronic, and check for symptoms like confusion, seizures, or coma which would indicate severe hyponatremia requiring urgent treatment. For severe symptomatic hyponatremia, administer 3% hypertonic saline at 100-150ml over 10-20 minutes, which can be repeated up to 2-3 times if symptoms persist. The goal is to raise sodium by 4-6 mmol/L in the first 6 hours to alleviate severe symptoms. For chronic or asymptomatic hyponatremia, identify the underlying cause by assessing volume status (hypovolemic, euvolemic, or hypervolemic) and measuring urine osmolality and sodium. Some key points to consider in the approach include:

• Fluid restriction to 800-1000ml/day is often the first-line treatment for euvolemic hyponatremia.
• For hypovolemic hyponatremia, isotonic saline (0.9% NaCl) should be administered.
• In hypervolemic states, fluid restriction and loop diuretics like furosemide 20-40mg daily may be needed, as suggested by the 2013 ACCF/AHA guideline for the management of heart failure 1. Importantly, sodium correction should not exceed 8 mmol/L in 24 hours (or 6 mmol/L in high-risk patients) to prevent osmotic demyelination syndrome, and regular monitoring of serum sodium (every 2-4 hours initially) is essential during correction. It is also crucial to consider the use of vasopressin antagonists, such as tolvaptan, in patients with hypervolemic hyponatremia who are at risk for or having active cognitive symptoms, as they may improve serum sodium concentration in the short term, according to the 2013 ACCF/AHA guideline 1. However, the long-term safety and benefit of this approach remain unknown, and the 2022 AHA/ACC/HFSA guideline suggests that fluid restriction has limited-to-no effect on clinical outcomes or diuretic use in patients with heart failure 1.

From the FDA Drug Label

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 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.

For a 78-year-old patient with hyponatremia, the approach as per NICD guidance is to:

• Initiate therapy in a hospital to closely monitor serum sodium levels and evaluate the therapeutic response.
• Start with a low dose of 15 mg once daily and titrate as needed to a maximum of 60 mg once daily.
• Monitor serum sodium levels and neurologic status closely, especially during initiation and after titration, to avoid too rapid correction of hyponatremia.
• Avoid fluid restriction during the first 24 hours of therapy to minimize the risk of overly rapid correction of serum sodium 2.

From the Research

Approach to Hyponatremia in a 78-Year-Old Patient

According to the provided evidence, hyponatremia is a common electrolyte disorder that affects approximately 5% of adults and 35% of hospitalized patients 3. In older patients, chronic hyponatremia can often be the result of medications used to treat chronic disease 4.

Diagnosis and Management

The approach to managing hyponatremia should consist of treating the underlying cause 3. The following steps can be taken:

• Evaluate the patient's fluid volume status (hypovolemic, euvolemic, or hypervolemic hyponatremia) 3, 5
• Assess the patient's symptoms and signs of hyponatremia, which can range from mild and nonspecific to severe and life-threatening 3
• Use laboratory parameters such as serum sodium, urine electrolytes, and serum and urine osmolality to aid in diagnosis 5, 6
• Consider point-of-care ultrasonography as an adjunct to physical assessment in estimation of volume status 6

Treatment Options

Treatment options for hyponatremia include:

• Fluid restriction, which can be an effective therapy in dilutional hyponatremia, although poor compliance and the burdensome nature of the restrictions are important considerations 4
• Urea and vaptans, which can be effective treatments for the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure, but have adverse effects 3
• Tolvaptan, an oral vasopressin receptor antagonist that can increase serum sodium concentrations by increasing electrolyte-free water excretion, which is supported by clinical trial evidence in patients with hypervolaemic or euvolaemic hyponatraemia below 125 mmol/L 4
• Hypertonic saline, which is reserved for patients with severely symptomatic hyponatremia, and should be used to increase the serum sodium level by 4 mEq/L to 6 mEq/L within 1 to 2 hours, but by no more than 10 mEq/L within the first 24 hours 3, 5, 7

Considerations in Older Patients

In older patients, hyponatremia can be caused by medications used to treat chronic disease, and treatment should be tailored to the individual patient's needs 4. Additionally, older patients may be more susceptible to the adverse effects of treatment, and careful monitoring is necessary to avoid overly rapid correction of hyponatremia, which can cause osmotic demyelination, a rare but severe neurological condition 3.