How to manage hyponatremia in elderly patients?

Management of Hyponatremia in Elderly Patients

The management of hyponatremia in elderly patients should be based on the underlying cause, severity, chronicity, and volume status, with correction rates not exceeding 10 mEq/L in 24 hours to avoid osmotic demyelination syndrome. 1

Assessment and Diagnosis

• Hyponatremia should be investigated when serum sodium is less than 131 mmol/L 1
• Classify hyponatremia based on volume status as hypovolemic, euvolemic, or hypervolemic 2
• Evaluation should include physical examination findings, basic laboratory studies, and when available, invasive monitoring 1
• In elderly patients with volume depletion following vomiting or diarrhea, check for: confusion, non-fluent speech, extremity weakness, dry mucous membranes, dry tongue, furrowed tongue, and sunken eyes (presence of ≥4 signs indicates moderate to severe volume depletion) 1
• Postural pulse change (≥30 beats per minute) or severe postural dizziness causing inability to stand suggests significant volume depletion 1
• Measure serum and urine osmolality and urine sodium concentration to help establish underlying causes 3

Treatment Approach Based on Volume Status

1. Hypovolemic Hyponatremia

• Administer isotonic fluids (oral, nasogastric, subcutaneous, or intravenous) to replace lost water and electrolytes 1
• Discontinue diuretics and/or laxatives if they are contributing factors 1
• For elderly patients unable to drink with severe dehydration (measured serum osmolality >300 mOsm/kg), intravenous fluids should be considered 1

2. Euvolemic Hyponatremia (often SIADH in elderly)

• First-line: Identify and discontinue medications that may cause SIADH 4
• Second-line: Fluid restriction (typically to 1,000 mL/day for moderate hyponatremia) 1, 4
• Third-line: Consider vasopressin receptor antagonists (vaptans) for persistent cases 4
• Urea, diuretics, lithium, and demeclocycline are alternative options for SIADH 1

3. Hypervolemic Hyponatremia

• Fluid restriction is the mainstay of treatment but often has limited efficacy 1
• Reduce or discontinue diuretics if they are contributing to hyponatremia 1
• In cirrhosis with ascites:
  • Mild hyponatremia (126-135 mEq/L): Monitor and restrict water 1
  • Moderate hyponatremia (120-125 mEq/L): Fluid restriction to 1,000 mL/day 1
  • Severe hyponatremia (<120 mEq/L): More severe fluid restriction plus albumin infusion 1
• In heart failure:
  • Vasopressin antagonists may be considered for persistent severe hyponatremia with cognitive symptoms despite water restriction and maximized GDMT 1

Correction Rate Guidelines

• Do not correct serum sodium by more than 10 mEq/L in 24 hours 1
• For severely symptomatic hyponatremia (somnolence, seizures, coma), use hypertonic saline to increase sodium by 4-6 mEq/L within 1-2 hours 2
• Goal rate of change for serum sodium: 4-8 mEq/L per day 1
• Overly rapid correction of chronic hyponatremia can lead to osmotic demyelination syndrome (ODS) 1, 2

Special Considerations for Elderly

• Elderly patients are at higher risk for hyponatremia due to age-related changes in water homeostasis 4
• Mild chronic hyponatremia in elderly is associated with cognitive impairment, gait disturbances, and increased rates of falls and fractures 2
• Elderly patients with hyponatremia have a 23.8% history of falls (vs 16.4% in those with normal sodium levels) 2
• Hyponatremia is a secondary cause of osteoporosis in elderly patients 2
• Tolvaptan (vasopressin V2-receptor antagonist) may be used in elderly patients, but caution is needed as no differences in safety were observed between elderly and younger patients, though greater sensitivity in some older individuals cannot be ruled out 5

Pharmacological Options

• Tolvaptan: Selective vasopressin V2-receptor antagonist for euvolemic or hypervolemic hyponatremia 5
  • Not recommended in patients with CrCl <10 mL/min 5
  • Monitor for overly rapid correction of sodium and increased thirst 2
• Albumin infusion: Associated with improvement in hyponatremia in hospitalized patients with cirrhosis 1
• Fludrocortisone: May be considered in hyponatremia associated with cerebral salt wasting 1
• Hypertonic (3%) saline: Reserved for severely symptomatic hyponatremia 2, 3

Pitfalls to Avoid

• Fluid restriction is not necessary in most patients with cirrhosis and ascites unless serum sodium is <120-125 mmol/L 1
• Rapid correction of chronic hyponatremia can lead to osmotic demyelination syndrome, especially in elderly with risk factors such as malnutrition 1
• Hypertonic saline should be used cautiously as it can lead to more complications than the hyponatremia itself if correction is too rapid 1
• Do not delay treatment while pursuing diagnosis in severely symptomatic patients 6
• Avoid treating hyponatremia with fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 1