What are the implications and treatment for a patient with hyponatremia?

Management of Severe Hyponatremia (Sodium 107.7 mmol/L)

This patient requires immediate hospitalization with urgent hypertonic saline administration, as a sodium level of 107.7 mmol/L represents life-threatening severe hyponatremia that demands emergency intervention. 1

Immediate Emergency Management

Administer 3% hypertonic saline immediately as 100 mL intravenous bolus over 10 minutes, which can be repeated up to three times at 10-minute intervals until severe symptoms improve. 1, 2 The initial goal is to correct sodium by 6 mmol/L over the first 6 hours or until severe symptoms (seizures, coma, altered mental status) resolve. 1

Critical Correction Rate Limits

• Maximum correction must not exceed 8 mmol/L in the first 24 hours to prevent osmotic demyelination syndrome 1, 3
• For high-risk patients (advanced liver disease, alcoholism, malnutrition), limit correction to 4-6 mmol/L per day 1
• The FDA specifically warns that correction >12 mEq/L/24 hours can cause osmotic demyelination resulting in dysarthria, mutism, dysphagia, lethargy, spastic quadriparesis, seizures, coma and death 3

Intensive Monitoring Protocol

• Check serum sodium every 2 hours during initial correction phase 1
• After severe symptoms resolve, monitor every 4 hours 1
• Continuous clinical assessment for neurological changes 1

Diagnostic Workup (Concurrent with Treatment)

While initiating treatment, obtain:

• Serum and urine osmolality 1
• Urine sodium and electrolytes 1
• Serum uric acid (levels <4 mg/dL suggest SIADH with 73-100% positive predictive value) 1
• Assessment of extracellular fluid volume status (orthostatic hypotension, dry mucous membranes, skin turgor, jugular venous distention, peripheral edema, ascites) 1

Do not delay treatment while pursuing diagnostic workup. 4

Post-Acute Management Based on Etiology

For SIADH (Euvolemic Hyponatremia)

Once severe symptoms resolve and sodium reaches safer levels (>120 mmol/L):

• Implement fluid restriction to 1 L/day 1
• If no response to fluid restriction, add oral sodium chloride 100 mEq three times daily 1
• Consider tolvaptan 15 mg once daily for resistant cases, but only after initial stabilization 3

For Cerebral Salt Wasting (Hypovolemic)

• Continue volume and sodium replacement with isotonic or hypertonic saline 1
• Add fludrocortisone for severe symptoms or in subarachnoid hemorrhage patients 1
• Never use fluid restriction in cerebral salt wasting as this worsens outcomes 1

For Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

• Fluid restriction to 1-1.5 L/day once stabilized 1
• Consider albumin infusion in cirrhotic patients 1
• Temporarily discontinue diuretics until sodium improves 1

Management of Overcorrection

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

• Immediately discontinue current fluids and switch to D5W (5% dextrose in water) 1
• Consider administering desmopressin to slow or reverse the rapid rise 1
• Target reduction to bring total 24-hour correction to no more than 8 mmol/L from starting point 1

Common Pitfalls to Avoid

• Never use fluid restriction as initial treatment for severe symptomatic hyponatremia - this is a medical emergency requiring hypertonic saline 1
• Never exceed 8 mmol/L correction in 24 hours - overcorrection risks osmotic demyelination syndrome 1, 3
• Inadequate monitoring during active correction can lead to complications 1
• Failing to distinguish between SIADH and cerebral salt wasting in neurosurgical patients leads to opposite and potentially harmful treatments 1
• Using fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm worsens outcomes 1

Special High-Risk Populations

Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require even more cautious correction at 4-6 mmol/L per day due to substantially higher risk of osmotic demyelination syndrome. 1, 3 In these patients, slower correction rates may be advisable even in the acute setting. 3

Clinical Significance

Even mild hyponatremia is associated with increased mortality, with sodium levels <130 mmol/L linked to a 60-fold increase in hospital fatality (11.2% versus 0.19%). 1 At 107.7 mmol/L, this represents an immediately life-threatening emergency requiring ICU-level care with continuous monitoring. 1, 2