How to manage severe hyponatremia of 112 mmol/L?

Management of Severe Hyponatremia (Sodium 112 mmol/L)

For severe hyponatremia at 112 mmol/L, immediately administer 3% hypertonic saline with a target correction of 6 mmol/L over the first 6 hours or until severe symptoms resolve, but never exceed 8 mmol/L total correction in 24 hours to prevent osmotic demyelination syndrome. 1

Immediate Assessment and Emergency Management

Determine symptom severity first - this dictates urgency of treatment:

• Severe symptoms (seizures, coma, altered mental status, cardiorespiratory distress) require immediate hypertonic saline 1, 2
• Mild symptoms (nausea, vomiting, headache, weakness) allow for more measured approach 3
• Asymptomatic patients can be managed more conservatively 4

For severe symptomatic hyponatremia at 112 mmol/L:

• Administer 3% hypertonic saline as 100 mL boluses over 10 minutes 1
• Can repeat up to three times at 10-minute intervals until symptoms improve 1
• Target: increase sodium by 6 mmol/L over first 6 hours 1, 2
• Critical safety limit: maximum 8 mmol/L correction in 24 hours 1, 2, 3

Volume Status Assessment

Determine if hypovolemic, euvolemic, or hypervolemic - this guides definitive treatment:

• Hypovolemic signs: orthostatic hypotension, dry mucous membranes, decreased skin turgor, flat neck veins 1
• Euvolemic: no edema, normal blood pressure, moist mucous membranes 1
• Hypervolemic signs: peripheral edema, ascites, jugular venous distention 1

Check urine sodium to confirm volume status:

• Urine sodium <30 mmol/L suggests hypovolemic hyponatremia responsive to saline 1
• Urine sodium >20-40 mmol/L with high urine osmolality (>300 mOsm/kg) suggests SIADH 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

• Administer isotonic (0.9%) saline for volume repletion 1
• Once euvolemic, reassess and adjust management 1

Euvolemic Hyponatremia (SIADH)

• After acute correction: implement fluid restriction to 1 L/day 1, 2
• Add oral sodium chloride 100 mEq three times daily if no response to fluid restriction 1
• Consider vaptans (tolvaptan 15 mg daily) for resistant cases, but use cautiously due to risk of overly rapid correction 5, 2

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

• Implement fluid restriction to 1-1.5 L/day 1
• Avoid hypertonic saline unless life-threatening symptoms present - it worsens edema and ascites 1
• Consider albumin infusion in cirrhotic patients 1
• Discontinue diuretics temporarily 1

Critical Monitoring Protocol

During active correction:

• Check serum sodium every 2 hours during initial correction phase 1
• Once severe symptoms resolve, check every 4 hours 1
• Continue daily monitoring until stable 1

Calculate sodium deficit:

• Formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1

High-Risk Populations Requiring Slower Correction

Limit correction to 4-6 mmol/L per day (not exceeding 8 mmol/L in 24 hours) in:

• Advanced liver disease 1, 4
• Alcoholism 1, 4
• Malnutrition 1, 4
• Prior encephalopathy 1
• Chronic hyponatremia (>48 hours duration) 1, 4

Management of Overcorrection

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

• Immediately discontinue current fluids 1
• Switch to D5W (5% dextrose in water) to relower sodium 1
• Consider administering desmopressin to slow or reverse rapid rise 1
• Monitor for osmotic demyelination syndrome signs: dysarthria, dysphagia, oculomotor dysfunction, quadriparesis (typically 2-7 days after rapid correction) 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 - overly rapid correction causes osmotic demyelination syndrome 1, 2, 6
• Never use hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms - worsens fluid overload 1
• Never ignore mild hyponatremia - even levels of 130-135 mmol/L increase fall risk and mortality 1, 2
• Inadequate monitoring during active correction leads to overcorrection 1

Special Considerations

In neurosurgical patients, distinguish between SIADH and cerebral salt wasting (CSW):

• CSW requires volume and sodium replacement, not fluid restriction 1
• Fluid restriction in CSW worsens outcomes 1
• Consider fludrocortisone for CSW in subarachnoid hemorrhage patients 1

In cirrhotic patients:

• Higher risk of gastrointestinal bleeding with tolvaptan (10% vs 2% placebo) 5
• Hyponatremia increases risk of spontaneous bacterial peritonitis (OR 3.40), hepatorenal syndrome (OR 3.45), and hepatic encephalopathy (OR 2.36) 1