What are the treatment approaches for hyponatremia (low sodium levels) and hypernatremia (high sodium levels)?

Treatment Approaches for Hyponatremia and Hypernatremia

The treatment of hyponatremia and hypernatremia must be guided by the underlying cause, severity of symptoms, and volume status, with correction rates carefully controlled to prevent neurological complications.

Hyponatremia Treatment

Classification and Evaluation

• Hyponatremia (serum sodium <135 mmol/L) should be evaluated based on volume status (hypovolemic, euvolemic, or hypervolemic) and serum osmolality 1
• Initial workup should include serum and urine osmolarity, urine electrolytes, uric acid, and assessment of extracellular fluid volume status 1
• Pseudohyponatremia from hyperglycemia or hypertriglyceridemia should be ruled out before treatment 1

Rate of Correction

• The rate of correction should be determined by symptom severity and onset timing, with a maximum increase of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1
• For severe symptoms (seizures, coma), correct by 6 mmol/L over 6 hours or until symptoms improve 1
• For chronic hyponatremia, avoid rapid correction exceeding 1 mmol/L/hour 1
• Patients with advanced liver disease require even more cautious correction (4-6 mmol/L per day) due to higher risk of osmotic demyelination 1

Treatment Based on Etiology

Syndrome of Inappropriate ADH (SIADH)

• For mild/asymptomatic SIADH: Fluid restriction to 1L/day is the cornerstone of treatment 1, 2
• For severe symptomatic SIADH: 3% hypertonic saline with careful monitoring 1, 3
• Additional options for refractory cases:
  • Salt tablets (100 mEq TID) 1
  • High protein diet 1
  • Urea or vaptans may be considered in selected cases 1, 3

Cerebral Salt Wasting (CSW)

• Treatment focuses on volume and sodium replacement 1
• Severe symptoms require ICU admission with 3% hypertonic saline and fludrocortisone 1
• Normal saline infusion should be added if no response to initial treatment 1
• Fluid restriction is contraindicated in CSW as it may worsen cerebral ischemia 1

Hypovolemic Hyponatremia

• Discontinue diuretics if applicable 1
• Administer isotonic saline (0.9% NaCl) for volume repletion 1, 4
• For severe symptoms, 3% hypertonic saline may be required with careful monitoring 4

Hypervolemic Hyponatremia (e.g., cirrhosis, heart failure)

• Fluid restriction to 1000 mL/day for moderate hyponatremia (120-125 mmol/L) 1
• More severe fluid restriction plus albumin infusion for severe hyponatremia (<120 mmol/L) 1
• Avoid hypertonic saline in hypervolemic states unless life-threatening symptoms are present 1
• Treat underlying condition (heart failure, cirrhosis) 5

Special Considerations

• Monitor serum sodium every 2-4 hours during active correction of severe hyponatremia 1
• If overcorrection occurs, consider desmopressin to relower sodium and prevent osmotic demyelination 6
• Avoid medications that can worsen hyponatremia (tricyclic antidepressants, SSRIs, carbamazepine, etc.) 6

Hypernatremia Treatment

General Approach

• Identify and treat the underlying cause (diabetes insipidus, dehydration, etc.) 5
• Calculate the free water deficit and replace gradually 5
• For mild cases, oral hypotonic fluids are preferred 5
• For severe cases, intravenous hypotonic solutions (0.45% saline or 5% dextrose) may be required 5

Rate of Correction

• Similar to hyponatremia, avoid rapid correction of chronic hypernatremia 5
• Maximum decrease of 8-10 mmol/L per 24 hours to prevent cerebral edema 5

Common Pitfalls to Avoid

• Treating the laboratory value without considering clinical symptoms 2, 7
• Overly rapid correction of chronic hyponatremia leading to osmotic demyelination syndrome 1, 3
• Inadequate monitoring during active correction 1, 4
• Using fluid restriction in CSW, which can worsen outcomes 1
• Failing to recognize and treat the underlying cause 1, 2
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1