What is the management for severe hyponatremia?

Management of Severe Hyponatremia (Sodium 116 mmol/L)

For a sodium level of 116 mmol/L, you must immediately assess symptom severity: if the patient has severe symptoms (seizures, altered mental status, coma), administer 3% hypertonic saline with a target correction of 6 mmol/L over 6 hours; if asymptomatic or mildly symptomatic, implement fluid restriction to 1-1.5 L/day and determine the underlying cause (hypovolemic, euvolemic, or hypervolemic) to guide further management. 1

Immediate Assessment Required

Symptom Severity Classification

• Severe symptoms requiring emergency treatment include: seizures, coma, altered mental status, confusion, obtundation, or cardiorespiratory distress 1, 2
• Mild symptoms include: nausea, vomiting, weakness, headache, or mild cognitive deficits 2, 3
• Even if asymptomatic, sodium <120 mmol/L carries significant risk with 60-fold increased mortality (11.2% vs 0.19%) and 21% fall risk compared to 5% in normonatremic patients 1

Volume Status Determination

• Hypovolemic signs: orthostatic hypotension, dry mucous membranes, decreased skin turgor, tachycardia 1, 3
• Euvolemic signs: no edema, normal blood pressure, moist mucous membranes 1
• Hypervolemic signs: peripheral edema, ascites, jugular venous distention, pulmonary congestion 1, 3

Emergency Management for Severe Symptoms

Hypertonic Saline Protocol

• Administer 3% hypertonic saline as 100 mL boluses over 10 minutes, repeatable up to three times at 10-minute intervals 1
• Target correction: 6 mmol/L over the first 6 hours or until severe symptoms resolve 1, 2
• Monitor serum sodium every 2 hours during initial correction phase 1
• Critical safety limit: total correction must NOT exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 2, 3

High-Risk Populations Requiring Slower Correction

• Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require even more cautious correction at 4-6 mmol/L per day maximum 1, 4
• These patients have 0.5-1.5% risk of osmotic demyelination syndrome even with appropriate correction rates 1

Management Based on Volume Status (For Non-Emergency Cases)

Hypovolemic Hyponatremia

• Discontinue diuretics immediately 1
• Administer isotonic (0.9%) saline for volume repletion 1, 3
• Urine sodium typically <30 mmol/L in hypovolemic states 1
• Continue isotonic fluids until euvolemia achieved 1

Euvolemic Hyponatremia (SIADH)

• Fluid restriction to 1 L/day is the cornerstone of treatment 1, 3, 5
• If no response to fluid restriction after 24-48 hours, add oral sodium chloride 100 mEq three times daily 1
• For persistent cases despite fluid restriction, consider tolvaptan 15 mg once daily with careful monitoring 1, 6
• Avoid fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 1

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

• Fluid restriction to 1-1.5 L/day for sodium <125 mmol/L 1, 3
• Discontinue diuretics temporarily until sodium improves 1
• For cirrhotic patients, consider albumin infusion alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms present, as it worsens ascites and edema 1
• Sodium restriction (not fluid restriction) results in weight loss as fluid follows sodium in cirrhosis 1

Critical Monitoring Requirements

During Active Correction

• Severe symptoms: check serum sodium every 2 hours initially 1
• Mild symptoms: check serum sodium every 4 hours 1
• After symptom resolution: check daily, then adjust frequency based on response 1
• Track daily weights and fluid balance meticulously 1

Signs of Osmotic Demyelination Syndrome

• Watch for dysarthria, dysphagia, oculomotor dysfunction, quadriparesis, or parkinsonism 1, 2
• Symptoms typically occur 2-7 days after rapid correction 1
• If overcorrection occurs (>8 mmol/L in 24 hours), immediately discontinue current fluids, switch to D5W, and consider desmopressin 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 for chronic hyponatremia (>48 hours duration) 1, 2, 3
• Never use fluid restriction in cerebral salt wasting—this worsens outcomes and requires volume/sodium replacement instead 1
• Never ignore mild hyponatremia (130-135 mmol/L) as clinically insignificant—it increases fall risk and mortality 1
• Never use lactated Ringer's solution for hyponatremia treatment due to its hypotonic nature (130 mEq/L sodium) 1