When should a patient with hyponatremia, possibly with underlying conditions such as heart failure, liver disease, or kidney disease, be admitted to the hospital?

When to Admit Hyponatremia

Admit patients with hyponatremia to the hospital when serum sodium is <125 mEq/L, when any neurological symptoms are present regardless of sodium level, or when rapid correction with hypertonic saline is required.

Mandatory Hospital Admission Criteria

Patients requiring hospital admission include those with severe hyponatremia (<120 mEq/L), any symptomatic hyponatremia with neurological manifestations, or when initiating vaptan therapy. 1

Absolute Indications for Admission

• Severe hyponatremia with serum sodium <120 mEq/L requires hospitalization regardless of symptoms, as this level carries a 60-fold increase in mortality (11.2% vs 0.19% in normonatremic patients) and is associated with significant morbidity 2, 3

• Any neurological symptoms including seizures, altered mental status, confusion, coma, somnolence, obtundation, or cardiorespiratory distress mandate immediate admission for hypertonic saline administration 2, 3, 4

• Acute hyponatremia (<48 hours duration) with sodium <125 mEq/L requires admission due to risk of explosive neurological deterioration, particularly in postoperative patients or those receiving excessive hypotonic fluids 5

• Initiation or re-initiation of tolvaptan therapy must occur in hospital with close serum sodium monitoring to prevent overly rapid correction and osmotic demyelination syndrome 1

Relative Indications for Admission

• Moderate symptomatic hyponatremia (sodium 120-125 mEq/L) with symptoms such as nausea, vomiting, confusion, headache, or gait instability should be admitted for monitored correction 6, 2, 7

• Hyponatremia in high-risk populations including patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require admission for cautious correction at 4-6 mEq/L per day 2, 5

• Hyponatremia with underlying critical illness such as sepsis, respiratory failure, or hypoxia requires ICU admission, as these factors predict poor outcome with mortality rates exceeding 20% 8, 4

• Pediatric patients with hyponatremia and altered clinical status (seizures or altered mental status) require intermediate care or ICU admission for cardiac monitoring and therapeutic intervention 6

Outpatient Management Considerations

Patients with chronic asymptomatic hyponatremia and sodium 126-135 mEq/L may be managed outpatient with close monitoring if they have stable underlying conditions and reliable follow-up 2

• Outpatient management is appropriate for euvolemic or hypervolemic hyponatremia with sodium >125 mEq/L without symptoms, using fluid restriction to 1-1.5 L/day 2

• Patients on diuretics with sodium 126-135 mEq/L and normal creatinine can continue therapy with close electrolyte monitoring without admission 2

• Chronic hyponatremia in cirrhotic patients with sodium 130-135 mEq/L is often tolerated without specific treatment beyond managing the underlying condition 2

Critical Safety Considerations During Admission

• Monitor serum sodium every 2 hours during initial correction for severe symptomatic patients, and every 4 hours after symptom resolution 2

• Never exceed 8 mEq/L correction in 24 hours to prevent osmotic demyelination syndrome; high-risk patients require even slower correction at 4-6 mEq/L per day 2, 1, 5

• For severe symptoms, correct by 6 mEq/L over first 6 hours or until symptoms resolve using 3% hypertonic saline, then limit total correction to 8 mEq/L in 24 hours 2, 3

• Patients with sepsis, respiratory failure, or hypoxia require ICU-level care as these factors strongly predict mortality in severe hyponatremia 4

Common Pitfalls to Avoid

• Do not discharge patients with sodium <125 mEq/L even if asymptomatic, as this level is associated with increased falls (21% vs 5%), fractures, and progression to severe complications 2, 3

• Do not ignore mild hyponatremia (130-135 mEq/L) in neurosurgical patients, as it may indicate cerebral salt wasting or SIADH requiring closer monitoring and potential admission 2

• Do not attempt outpatient correction with hypertonic saline or vaptans, as these require hospital monitoring to prevent overly rapid correction 1

• Recognize that slow correction rates in severe symptomatic hyponatremia are associated with higher mortality than appropriately rapid initial correction, particularly in the presence of neurological symptoms 4, 5