What is the management for a patient with hyponatremia?

Management of Hyponatremia (Sodium 130 mmol/L)

For a patient with hyponatremia (sodium 130 mmol/L), management depends critically on volume status and symptom severity, but the first step is always to assess whether the patient is hypovolemic, euvolemic, or hypervolemic, as this determines the treatment approach. 1

Initial Assessment

Determine volume status immediately by examining for orthostatic hypotension, dry mucous membranes, poor skin turgor (hypovolemia), versus jugular venous distention, peripheral edema, ascites (hypervolemia), versus absence of these findings (euvolemia). 1, 2

Obtain the following laboratory tests to guide management:

• Serum and urine osmolality 1
• Urine sodium concentration 1, 3
• Urine electrolytes 1
• Serum uric acid 1
• Thyroid-stimulating hormone (TSH) to exclude hypothyroidism 1
• Serum creatinine and blood urea nitrogen 1

A urine sodium <30 mmol/L suggests hypovolemic hyponatremia with 71-100% positive predictive value for response to normal saline.** 1 **A urine sodium >20 mEq/L with high urine osmolality (>500 mOsm/kg) suggests SIADH. 1

Symptom Assessment

At sodium 130 mmol/L, most patients have mild or no symptoms. 3 However, even mild hyponatremia (130-135 mmol/L) should not be ignored as it increases fall risk (23.8% vs 16.4% in normonatremic patients) and is associated with increased mortality. 1, 2

Mild symptoms include nausea, vomiting, weakness, headache, and mild neurocognitive deficits. 3 Severe symptoms (seizures, coma, confusion, impaired consciousness) are rare at this sodium level but require emergency treatment with 3% hypertonic saline if present. 1, 3

Treatment Based on Volume Status

Hypovolemic Hyponatremia

Discontinue diuretics immediately and administer isotonic saline (0.9% NaCl) for volume repletion. 1, 3 This is appropriate when urine sodium is <30 mmol/L and there are clinical signs of volume depletion. 1

Do not exceed correction of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1, 2

Euvolemic Hyponatremia (SIADH)

Fluid restriction to 1 L/day (or <1 L/day) is the cornerstone of treatment for SIADH. 1, 3, 4

If fluid restriction alone is ineffective after several days:

• Add oral sodium chloride tablets 100 mEq three times daily 1
• Consider urea (effective but has poor palatability and gastric intolerance) 1, 2
• Consider demeclocycline, lithium, or loop diuretics for resistant cases 1, 5

For persistent severe hyponatremia despite conventional therapy, tolvaptan (a vasopressin receptor antagonist) may be considered, starting at 15 mg once daily. 1, 6 However, tolvaptan carries risks of overly rapid correction and increased thirst. 2 Monitor sodium levels every 2-4 hours initially when using tolvaptan to avoid overcorrection. 1

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

Implement fluid restriction to 1-1.5 L/day, especially if sodium is <125 mmol/L. 1, 3, 5

Temporarily discontinue diuretics if sodium drops below 125 mmol/L. 1

For cirrhotic patients specifically:

• Consider albumin infusion alongside fluid restriction 1, 3
• Avoid hypertonic saline unless life-threatening symptoms are present, as it may worsen ascites and edema 1
• Note that it is sodium restriction, not fluid restriction, that results in weight loss as fluid passively follows sodium 1

In heart failure patients with persistent severe hyponatremia despite water restriction and maximization of guideline-directed medical therapy, vasopressin antagonists may be considered short-term. 1

Correction Rate Guidelines

The maximum correction rate should not exceed 8 mmol/L in 24 hours for all patients to prevent osmotic demyelination syndrome. 1, 2, 3, 4

For patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy, use even more cautious correction rates of 4-6 mmol/L per day due to higher risk of osmotic demyelination. 1, 2

Monitoring

• Check sodium levels every 4-6 hours initially during active correction 1
• Once stable, monitor daily 1
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 1

Common Pitfalls to Avoid

Overly rapid correction exceeding 8 mmol/L in 24 hours leading to osmotic demyelination syndrome is the most critical error to avoid. 1, 2, 4

Inadequate monitoring during active correction can lead to unrecognized overcorrection. 1

Failing to identify and treat the underlying cause will result in recurrent hyponatremia. 1, 5

Using fluid restriction in cerebral salt wasting (CSW) can worsen outcomes—CSW requires volume and sodium replacement, not restriction. 1 This distinction is particularly important in neurosurgical patients. 1

Ignoring mild hyponatremia (130-135 mmol/L) as clinically insignificant is a mistake, as it increases fall risk and mortality. 1, 2