How to manage a patient with hyponatremia (sodium level 129 mmol/L) and a left hip fracture?

Management of Hyponatremia (Na 129 mmol/L) in a Hip Fracture Patient

Do not delay surgery to correct mild hyponatremia—proceed to surgery within 48 hours while investigating and treating the underlying cause, as surgical delay significantly increases mortality and morbidity in hip fracture patients. 1, 2

Immediate Assessment and Workup

Determine the Underlying Cause

• Hyponatremia is common (17%) in hip fracture patients on admission and typically indicates infection or medication effects (particularly thiazide diuretics). 1
• Assess volume status clinically to categorize as hypovolemic, euvolemic, or hypervolemic hyponatremia—this guides treatment. 3, 4
• Check for signs of infection (chest, urine) as leukocytosis >17 × 10⁹/L may indicate infection, which commonly causes hyponatremia. 1
• Review medications immediately, especially thiazide diuretics, which are a frequent culprit. 1
• Obtain urea and electrolytes to assess for other abnormalities (hypokalaemia, hyperkalaemia from rhabdomyolysis if patient was immobilized). 1

Assess Symptom Severity

• At Na 129 mmol/L (mild hyponatremia), most patients are asymptomatic or have mild symptoms (nausea, weakness, headache). 4
• Severe symptoms (seizures, altered consciousness, coma) are rare at this level but require emergency treatment with 3% hypertonic saline if present. 3, 4
• Mild chronic hyponatremia is associated with cognitive impairment, gait disturbances, and increased fall/fracture risk—this patient likely already fell due to hyponatremia. 3

Pre-operative Management Strategy

Fluid and Electrolyte Management

• If hypovolemic (most common in hip fracture patients): administer normal saline IV to restore volume—many patients are hypovolaemic before surgery. 2, 4
• If euvolemic (SIADH suspected): implement fluid restriction to 1L/day, but do NOT use aggressive fluid restriction in hip fracture patients as this increases cerebral infarction risk. 1
• Prescribe pre-operative IV fluids routinely as cardiac output-guided fluid administration reduces hospital stay. 2

Specific Treatment Based on Etiology

• If medication-induced (thiazides): discontinue the offending agent immediately. 1
• If infection-related: treat infection promptly with antibiotics, supplemental oxygen, and IV fluids. 1
• Consider fludrocortisone 0.1 mg three times daily if cerebral salt wasting is suspected (reduces urinary sodium excretion). 1
• Avoid overly rapid correction—total correction should not exceed 8-10 mmol/L in first 24 hours to prevent osmotic demyelination syndrome. 3, 4

Surgical Timing and Anesthetic Considerations

Do Not Delay Surgery

• Surgery should proceed within 48 hours regardless of mild hyponatremia (Na 129 mmol/L), as delaying surgery beyond 48 hours significantly increases mortality, pneumonia, pressure sores, and thromboembolic complications. 2
• Chronic untreated hyponatremia is associated with increased long-term mortality after hip fracture repair, but this does not justify surgical delay. 5

Anesthetic Planning

• Regional anesthesia (spinal or epidural) is strongly preferred as it reduces sympathetic hyperactivity, allows early mobilization, and improves outcomes. 2
• If general anesthesia required, use invasive blood pressure monitoring given the electrolyte abnormality and likely cardiac comorbidities. 2
• Monitor sodium levels intraoperatively and postoperatively (Q4-6 hours initially). 1

Postoperative Management

Ongoing Monitoring and Treatment

• Continue treating the underlying cause (infection, medication adjustment, volume repletion). 3, 4
• Monitor sodium daily postoperatively—postoperative hyponatremia occurs in 2.8% of hip fracture patients. 6
• Maintain adequate hydration with goal-directed fluid therapy using cardiac output monitoring. 2
• Early mobilization is critical despite hyponatremia—improves outcomes and reduces complications. 2

Avoid Common Pitfalls

• Do not aggressively fluid-restrict hip fracture patients with hyponatremia—this increases cerebral infarction risk. 1
• Do not delay surgery for "optimization" of chronic electrolyte abnormalities—the fracture itself is the life-threatening emergency. 2
• Avoid NSAIDs entirely given likely renal dysfunction in elderly patients, which may worsen hyponatremia. 2
• Remove urinary catheter as soon as possible to reduce UTI risk, which can perpetuate hyponatremia. 2

Long-term Considerations

Chronic prolonged hyponatremia (>90 days) is independently associated with 4.5-fold increased hip fracture risk and 1.5-fold increased long-term mortality after hip fracture repair. 5, 7 Address the underlying cause definitively to prevent recurrence and improve long-term outcomes.