What is the treatment approach for an elderly patient with severe hyponatremia (serum sodium level less than 125 mmol/L) and symptomatic neurological symptoms?

Treatment of Severe Hyponatremia

For elderly patients with severe hyponatremia (serum sodium <125 mmol/L) and symptomatic neurological symptoms, immediately administer 3% hypertonic saline with a target correction of 6 mmol/L over 6 hours or until severe symptoms resolve, with total correction not exceeding 8 mmol/L in 24 hours. 1, 2, 3

Immediate Management for Severe Symptomatic Hyponatremia

Emergency Treatment Protocol

• Administer 3% hypertonic saline immediately for patients presenting with severe symptoms such as seizures, coma, confusion, altered mental status, or cardiorespiratory distress 1, 3, 4
• Bolus administration: Give 100 mL of 3% saline over 10 minutes, which can be repeated up to three times at 10-minute intervals until symptoms improve 1
• Target initial correction: Increase serum sodium by 6 mmol/L over the first 6 hours or until severe symptoms resolve 1, 2, 5
• After initial 6 mmol/L correction: Limit additional correction to only 2 mmol/L in the following 18 hours to stay within the 8 mmol/L per 24-hour limit 2

Critical Monitoring Requirements

• Check serum sodium every 2 hours during the initial correction phase for patients with severe symptoms 1, 4
• Transition to every 4-hour monitoring once severe symptoms resolve 1, 2
• Discontinue 3% saline when severe symptoms resolve, then switch to protocols for mild symptoms or asymptomatic hyponatremia 2

Correction Rate Guidelines and Safety Limits

Standard Correction Rates

• Maximum correction: 8 mmol/L in 24 hours for most patients to prevent osmotic demyelination syndrome 1, 3, 6
• Never exceed 12 mmol/L in 24 hours as this significantly increases risk of osmotic demyelination 7, 6, 8
• For the first 48 hours combined: Do not exceed 18 mmol/L total correction 6

High-Risk Populations Requiring Slower Correction

Elderly patients with severe hyponatremia often fall into high-risk categories requiring even more cautious correction at 4-6 mmol/L per day, maximum 8 mmol/L in 24 hours, particularly if they have: 1, 3, 4

• Advanced liver disease or cirrhosis 1, 7
• Chronic alcoholism 1, 7, 6
• Severe malnutrition 1, 7
• Prior history of encephalopathy 1
• Hypokalemia, hypophosphatemia, or hypoglycemia 1

Treatment Based on Volume Status

Assessment of Volume Status

After stabilizing severe symptoms, determine the underlying cause by assessing volume status: 1, 4

• Hypovolemic signs: Orthostatic hypotension, dry mucous membranes, decreased skin turgor, flat neck veins 1
• Euvolemic signs: Normal volume status, no edema, normal blood pressure 1
• Hypervolemic signs: Peripheral edema, ascites, jugular venous distention, pulmonary congestion 1

Hypovolemic Hyponatremia

• Discontinue diuretics immediately if sodium <125 mmol/L 1, 4
• Administer isotonic saline (0.9% NaCl) for volume repletion once severe symptoms are controlled 1, 4
• Initial infusion rate: 15-20 mL/kg/hour, then 4-14 mL/kg/hour based on response 1

Euvolemic Hyponatremia (SIADH)

• After severe symptoms resolve, implement fluid restriction to 1 L/day as the cornerstone of ongoing treatment 1, 2, 4
• Add oral sodium chloride 100 mEq three times daily if no response to fluid restriction 1
• Consider vasopressin receptor antagonists (tolvaptan 15 mg once daily) for resistant cases, but use with extreme caution to avoid overly rapid correction 1, 7

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

• Implement fluid restriction to 1-1.5 L/day for sodium <125 mmol/L 1, 4
• Temporarily discontinue diuretics until sodium improves 1
• Consider albumin infusion in cirrhotic patients alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms are present, as it may worsen edema and ascites 1

Special Considerations for Elderly Patients

Neurosurgical or CNS Pathology

In elderly patients with recent neurosurgery, stroke, or subarachnoid hemorrhage, distinguish between SIADH and cerebral salt wasting (CSW), as they require opposite treatments: 1, 4

• SIADH: Euvolemic state, treat with fluid restriction 1
• CSW: True hypovolemia with high urine sodium despite volume depletion, treat with volume and sodium replacement, NOT fluid restriction 1
• Consider fludrocortisone 0.1-0.2 mg daily for CSW in neurosurgical patients 1

Medication Review

Review and discontinue medications that may contribute to hyponatremia, including: 4

• Thiazide diuretics
• SSRIs and other antidepressants
• Carbamazepine
• NSAIDs
• Proton pump inhibitors

Prevention of Osmotic Demyelination Syndrome

Warning Signs of Overcorrection

Watch for signs of osmotic demyelination syndrome typically occurring 2-7 days after rapid correction: 1, 3

• Dysarthria (difficulty speaking)
• Dysphagia (difficulty swallowing)
• Oculomotor dysfunction
• Quadriparesis or spastic weakness
• Lethargy and affective changes
• Seizures or coma

Management of Overcorrection

If sodium correction exceeds 8 mmol/L in 24 hours: 1

• Immediately discontinue current fluids and switch to D5W (5% dextrose in water)
• Consider administering desmopressin to slow or reverse the rapid rise in serum sodium
• Relower sodium levels with electrolyte-free water if necessary

Common Pitfalls to Avoid

• Never use fluid restriction as initial treatment for altered mental status from severe hyponatremia—this is a medical emergency requiring hypertonic saline 1, 2
• Never exceed 8 mmol/L correction in 24 hours in elderly patients, especially those with risk factors for osmotic demyelination 1, 3, 6
• Never use fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 1, 2
• Never ignore mild hyponatremia (130-135 mmol/L) in elderly patients, as it increases fall risk and mortality 1, 3
• Never stop monitoring too early—inadequate monitoring during active correction is a common cause of complications 1