Management of Hyponatremia in Surgical Patients

Assessment and Classification

Hyponatremia should be evaluated based on volume status and serum osmolality to determine the underlying cause 1
Initial workup should include serum and urine osmolarity, urine electrolytes, uric acid, and assessment of extracellular fluid volume status 1
Hyponatremia is associated with increased hospital stay, mortality, and negative surgical outcomes across a broad range of primary disorders 2

Administer 3% hypertonic saline with a goal to correct 6 mmol/L over 6 hours or until severe symptoms resolve in severe symptomatic hyponatremia 1, 3
Total correction should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 4
For asymptomatic or mildly symptomatic patients, implement fluid restriction to 1 L/day 1, 3
Consider oral sodium supplementation for mild symptoms 5

Primary treatment for Syndrome of Inappropriate ADH (SIADH) is fluid restriction to 1 L/day 1, 3
May be treated with urea, diuretics, lithium, demeclocycline, and/or fluid restriction as second-line options for SIADH 4, 3
Treat cerebral salt wasting with replacement of serum sodium and intravenous fluids 4, 1
Fludrocortisone may be considered in subarachnoid hemorrhage patients at risk of vasospasm 4, 1
Hydrocortisone may be used to prevent natriuresis in subarachnoid hemorrhage patients 4
Fluid restriction should NOT be used in cerebral salt wasting as it can worsen outcomes 4, 1

The serum sodium level should not be corrected by more than 8 mmol/L/day to prevent osmotic demyelination syndrome 4, 1
Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require more cautious correction (4-6 mmol/L per day) 1
If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 1

Overly rapid correction of chronic hyponatremia leading to osmotic demyelination syndrome 1
Inadequate monitoring during active correction 1
Using fluid restriction in cerebral salt wasting 4, 1
Failing to recognize and treat the underlying cause 1, 3
Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1