How should hyponatremia with a serum sodium of 119 mmol/L be managed?

Management of Severe Hyponatremia (Sodium 119 mmol/L)

For a patient with serum sodium of 119 mmol/L, immediately assess symptom severity: if severe neurological symptoms (seizures, altered mental status, coma) are present, administer 3% hypertonic saline with a target correction of 6 mmol/L over 6 hours; if asymptomatic or mildly symptomatic, determine volume status (hypovolemic, euvolemic, or hypervolemic) to guide specific therapy, but never exceed 8 mmol/L correction in 24 hours regardless of approach. 1

Immediate Assessment Required

Symptom Severity Classification

• Severe symptoms requiring emergency treatment include seizures, coma, altered consciousness, confusion, delirium, or respiratory distress 1, 2
• Moderate symptoms include nausea, vomiting, headache, confusion, gait instability, and lethargy 2
• Mild or asymptomatic patients may have only weakness, mild cognitive changes, or no symptoms 2
• The rapidity of onset determines symptom severity more than the absolute sodium level—acute hyponatremia (<48 hours) causes more severe symptoms than chronic hyponatremia at the same sodium concentration 2

Determine Acuity of Onset

• Acute hyponatremia (<48 hours) typically occurs in hospital settings, postoperatively, or after excessive fluid administration, and can be corrected more rapidly without risk of osmotic demyelination 1, 3
• Chronic hyponatremia (>48 hours) usually develops outside the hospital and requires slower, more cautious correction due to brain adaptation mechanisms 1, 3

Emergency Management for Severe Symptomatic Hyponatremia

If the patient has severe neurological symptoms (seizures, coma, altered mental status), this is a medical emergency requiring immediate hypertonic saline—do not delay treatment to determine the underlying cause. 1, 4

Hypertonic Saline Protocol

• Administer 3% hypertonic saline as 100 mL boluses over 10 minutes, repeating up to three times at 10-minute intervals until symptoms improve 1, 5
• Target correction: increase serum sodium by 6 mmol/L over the first 6 hours or until severe symptoms resolve 1, 4
• Absolute maximum: do not exceed 8 mmol/L correction in any 24-hour period to prevent osmotic demyelination syndrome 1, 4
• Check serum sodium every 2 hours during initial correction phase 1
• ICU admission is required for close monitoring during active correction 1

Critical Safety Limits

• Standard-risk patients: maximum 8 mmol/L increase in 24 hours 1, 4
• High-risk patients (advanced liver disease, alcoholism, malnutrition, prior encephalopathy): maximum 4-6 mmol/L per day, absolute ceiling 8 mmol/L in 24 hours 1, 3
• Overly rapid correction (>8 mmol/L in 24 hours) causes osmotic demyelination syndrome, presenting 2-7 days later with dysarthria, dysphagia, oculomotor dysfunction, and quadriparesis 1

Management for Asymptomatic or Mildly Symptomatic Hyponatremia

For patients without severe symptoms, determine volume status through physical examination and laboratory studies to guide specific treatment—hypovolemic patients need volume repletion, euvolemic patients need fluid restriction or specific therapy for SIADH, and hypervolemic patients need fluid restriction and treatment of underlying disease. 1, 5

Initial Diagnostic Workup

• Obtain serum and urine osmolality, urine sodium concentration, serum creatinine, and assess extracellular fluid volume status 1
• Check thyroid-stimulating hormone (TSH) to exclude hypothyroidism 1
• Review all medications, particularly diuretics, SSRIs, carbamazepine, NSAIDs, and chemotherapy agents 1
• Do not delay treatment while awaiting ADH or natriuretic peptide levels—these tests are not supported by evidence and do not alter management 1

Volume Status Assessment

• Hypovolemic signs: orthostatic hypotension, dry mucous membranes, decreased skin turgor, flat neck veins, tachycardia 1
• Euvolemic signs: no edema, no orthostatic hypotension, normal skin turgor, moist mucous membranes 1
• Hypervolemic signs: peripheral edema, ascites, jugular venous distention, pulmonary congestion 1
• Physical examination alone has poor accuracy (sensitivity 41%, specificity 80%), so supplement with laboratory findings 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

• Discontinue diuretics immediately if sodium <125 mmol/L 1
• Administer isotonic saline (0.9% NaCl) for volume repletion at 15-20 mL/kg/h initially, then 4-14 mL/kg/h based on response 1
• Urine sodium <30 mmol/L predicts good response to saline infusion (positive predictive value 71-100%) 1
• In cirrhotic patients, consider albumin infusion (8 g per liter of ascites removed) alongside isotonic saline 1
• Maximum correction: 4-6 mmol/L per day for high-risk patients, 8 mmol/L in 24 hours absolute maximum 1

Euvolemic Hyponatremia (SIADH)

• Fluid restriction to 1 L/day is the cornerstone of treatment 1, 4
• If no response to fluid restriction after 24-48 hours, add oral sodium chloride 100 mEq three times daily 1
• For resistant cases, consider pharmacological options: urea, vasopressin receptor antagonists (tolvaptan 15 mg once daily, titrate to 30-60 mg), demeclocycline, or lithium 1, 4
• Urea provides effective water diuresis and may have lower risk of osmotic demyelination compared to hypertonic saline 3, 4
• Monitor serum sodium every 4-6 hours initially, then daily 1

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

• Fluid restriction to 1-1.5 L/day for serum sodium <125 mmol/L 1, 5
• Temporarily discontinue diuretics if sodium <125 mmol/L 1
• In cirrhotic patients, consider albumin infusion alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms are present, as it worsens ascites and edema 1
• Treat underlying disease (optimize heart failure therapy, manage cirrhosis) 1, 5
• Vasopressin receptor antagonists (tolvaptan) may be considered for persistent severe hyponatremia despite fluid restriction and optimization of guideline-directed therapy 1, 6

Special Considerations for Neurosurgical Patients

In patients with acute brain injury, subarachnoid hemorrhage, or other neurosurgical conditions, distinguish between SIADH and cerebral salt wasting (CSW) because they require opposite treatments—SIADH needs fluid restriction while CSW needs aggressive volume and sodium replacement. 1

Cerebral Salt Wasting (CSW)

• Treatment: aggressive volume and sodium replacement with isotonic or hypertonic saline (50-100 mL/kg/day), NOT fluid restriction 1
• For severe symptoms, use 3% hypertonic saline plus fludrocortisone 0.1-0.2 mg daily in ICU setting 1
• Hydrocortisone may prevent natriuresis in subarachnoid hemorrhage patients 1
• Never use fluid restriction in CSW—this worsens outcomes and can precipitate cerebral ischemia 1
• In subarachnoid hemorrhage patients at risk of vasospasm, avoid fluid restriction even if hyponatremia is present 1

Distinguishing SIADH from CSW

• SIADH: euvolemic, central venous pressure 6-10 cm H₂O, urine sodium >20-40 mEq/L, urine osmolality >300 mOsm/kg 1
• CSW: hypovolemic with orthostatic changes, central venous pressure <6 cm H₂O, urine sodium >20 mEq/L despite volume depletion, clinical signs of hypovolemia 1

Monitoring During Correction

Frequency of Sodium Checks

• Severe symptoms: every 2 hours during initial correction phase 1
• After symptom resolution: every 4 hours 1
• Mild symptoms or asymptomatic: every 4-6 hours initially, then daily 1

Calculating Sodium Deficit

• Use formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1
• This helps determine the appropriate amount of sodium supplementation needed 1

Signs of Osmotic Demyelination Syndrome

• Watch for dysarthria, dysphagia, oculomotor dysfunction, quadriparesis typically occurring 2-7 days after rapid correction 1
• If overcorrection occurs (>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 in serum sodium 1

Common Pitfalls to Avoid

• Never correct chronic hyponatremia faster than 8 mmol/L in 24 hours—this causes osmotic demyelination syndrome 1, 3
• Never use fluid restriction as initial treatment for severe symptomatic hyponatremia—this is a medical emergency requiring hypertonic saline 1
• Never use fluid restriction in cerebral salt wasting—this worsens outcomes 1
• Never ignore mild hyponatremia (130-135 mmol/L) as clinically insignificant—it increases mortality, falls, and cognitive impairment 1, 2
• Never delay treatment while pursuing a diagnosis—treat severe symptoms immediately 1, 5
• Inadequate monitoring during active correction leads to overcorrection and osmotic demyelination 1
• Failing to recognize and treat the underlying cause leads to recurrence 1

High-Risk Populations Requiring Extra Caution

• Advanced liver disease: maximum 4-6 mmol/L per day correction, risk of osmotic demyelination 0.5-1.5% even with careful correction 1
• Chronic alcoholism: higher risk of osmotic demyelination, limit correction to 4-6 mmol/L per day 1, 3
• Malnutrition: requires slower correction (4-6 mmol/L per day) 1, 3
• Prior hepatic encephalopathy: maximum 4-6 mmol/L per day 1
• Severe hyponatremia (<120 mmol/L): requires more cautious correction 1