What is the appropriate management of hyponatremia occurring during transurethral resection of the prostate (TURP)?

Management of Hyponatremia in TURP

For severe symptomatic hyponatremia during or after TURP (seizures, coma, marked mental status changes), immediately administer 3% hypertonic saline targeting a 6 mmol/L increase over 6 hours or until symptoms resolve, while ensuring total correction does not exceed 8 mmol/L in 24 hours. 1, 2

Severity-Based Treatment Algorithm

Severe Neurologic Symptoms (seizures, coma, altered mental status)

• Transfer immediately to ICU with continuous monitoring 1, 2
• Administer 3% hypertonic saline as 100-150 mL IV bolus or continuous infusion 1, 2, 3
  • Target: raise serum sodium by 6 mmol/L over first 6 hours 1, 2
  • Maximum correction: 8 mmol/L per 24 hours 1, 2
  • After initial 6 mmol/L correction, limit additional increase to 2 mmol/L over remaining 18 hours 1
• Check serum sodium every 2 hours during acute correction 1, 2
• Monitor strict intake/output and daily weights 1, 2
• Rapid correction at >1 mmol/L/hour is appropriate for acute symptomatic hyponatremia (<48 hours duration) 1

Critical distinction: TURP syndrome represents acute hyponatremia (developing over hours during surgery), not chronic hyponatremia. 4 Acute hyponatremia should be corrected rapidly because it causes severe cerebral edema and neurological complications. 4 Central pontine myelinolysis has not been reported after correction of acute hyponatremia in TURP patients—this complication occurs with overly rapid correction of chronic hyponatremia. 4

Mild Symptoms (nausea, vomiting, headache, mild confusion)

• Transfer to intermediate care unit 1, 2
• Check serum sodium every 4 hours 1, 2
• Implement fluid restriction to 1 L/day 1, 2
• Add oral sodium chloride 100 mEq three times daily if no response to fluid restriction 1, 2
• Consider furosemide 20 mg IV to promote free water excretion 5

Asymptomatic or Very Mild Hyponatremia

• Monitor serum sodium daily 1, 2
• Apply fluid restriction of 1 L/day 1, 2
• Advise high-protein diet 1, 2
• Continue until sodium reaches ≥131 mmol/L 1, 2

Special Considerations for TURP Syndrome

Mechanism and Pathophysiology

TURP syndrome results from excessive absorption of hypotonic irrigation fluid (typically glycine or sorbitol solutions) through prostatic venous sinuses during resection. 6, 5 This causes:

• Acute dilutional hyponatremia 6, 5
• Volume overload with pulmonary edema 6, 5
• Decreased serum osmolality 5
• Potential cardiovascular collapse 5

Important caveat: Some cases present as isotonic hyponatremia due to glycine absorption, where serum osmolality remains normal despite low sodium. 7 In these cases, neurologic symptoms may result from glycine toxicity rather than cerebral edema, and hypertonic saline may not be necessary. 7 Check serum osmolality and calculate the osmolar gap to guide therapy. 7

Patients with Cardiac or Renal Insufficiency

For TURP patients with severe hyponatremia (sodium <100 mmol/L) who develop pulmonary edema or cardiac decompensation after hypertonic saline administration, initiate continuous renal replacement therapy (CRRT). 6

• CRRT allows slow, controlled correction of hyponatremia while removing excess volume 6
• Prevents worsening of pulmonary edema and cardiac failure 6
• Avoids risk of overcorrection that can occur with hypertonic saline alone 6
• Particularly valuable when conventional treatment with hypertonic saline worsens volume overload 6

Respiratory Support

For patients developing pulmonary edema, provide CPAP-PSV with +5 cmH₂O PEEP, 8 cmH₂O pressure support, and FiO₂ 70-100%. 5

Prevention Strategies

Intraoperative Prophylaxis

Prophylactic administration of 2 mL/kg/hour of 3% hypertonic saline during TURP is superior to treating established TURP syndrome and prevents hyponatremia without causing hypernatremia. 8

• Low-dose prophylactic hypertonic saline (2 mL/kg/hour) is effective and safe 8
• Higher dose (4 mL/kg/hour) causes hypernatremia in 30% of patients 8
• Standard saline (6 mL/kg/hour) results in TURP syndrome in 25% of patients 8
• Prophylaxis reduces ICU admissions, need for postoperative ventilation, and hospital stay 8

Intraoperative Monitoring

Check serum sodium intraoperatively when the procedure is prolonged (>90 minutes) or when significant fluid absorption is suspected. 2, 4

Critical Correction Limits

Maximum Safe Correction Rates

• Total correction should not exceed 10 mmol/L per 24 hours 1, 2
• For severely symptomatic patients: 6 mmol/L over first 6 hours, then maximum 2 mmol/L over next 18 hours 1, 2
• Correction rates >1 mmol/L/hour reserved only for severely symptomatic acute hyponatremia 1

Recent evidence challenges traditional slow-correction dogma: A 2026 retrospective cohort of 13,988 patients with severe hyponatremia (≤120 mEq/L) found that faster correction rates (>12 mEq/L per 24 hours) were associated with 9 percentage points lower risk of 90-day death or delayed neurologic events compared to slow correction (<8 mEq/L per 24 hours). 9 However, this study included mixed etiologies of hyponatremia, and TURP syndrome represents a distinct acute scenario where rapid initial correction is already standard practice for symptomatic cases.

Preventing Osmotic Demyelination Syndrome

Overcorrection (>10 mmol/L per day) causes osmotic demyelination syndrome; prevent this by checking sodium every 2-4 hours during active correction and strict adherence to correction limits. 1, 2

• Osmotic demyelination occurs with overly rapid correction of chronic hyponatremia (>48 hours duration) 1
• TURP syndrome is acute hyponatremia and has different pathophysiology 4
• No cases of osmotic demyelination have been reported after correction of acute TURP-related hyponatremia 4
• If overcorrection occurs, administer hypotonic fluids or desmopressin to re-lower sodium 3

Common Pitfalls and How to Avoid Them

Pitfall 1: Treating the Number Instead of the Patient

Base management on symptom severity, not just the sodium value. 1, 2 A patient with sodium of 125 mmol/L and seizures requires aggressive treatment, while an asymptomatic patient with sodium of 120 mmol/L may need only fluid restriction and monitoring. 1

Pitfall 2: Applying Fluid Restriction to Volume-Depleted Patients

Assess volume status carefully before restricting fluids. 1, 2 Physical examination alone is unreliable (sensitivity 41%, specificity 80%). 1

• Check urine sodium: <30 mmol/L suggests volume depletion 1
• Consider central venous pressure measurement if uncertain 1
• Volume-depleted patients (cerebral salt wasting) require fluid and sodium replacement, not restriction 1
• TURP syndrome typically causes hypervolemia, making fluid restriction appropriate 5

Pitfall 3: Ignoring Isotonic Hyponatremia

Check serum osmolality and calculate osmolar gap when neurologic symptoms seem disproportionate to sodium level. 7 Glycine absorption can cause isotonic hyponatremia where cerebral edema is not the primary problem, and hypertonic saline may be unnecessary. 7

Pitfall 4: Inadequate Monitoring During Correction

Failure to check sodium frequently (every 2 hours for severe symptoms, every 4 hours for mild symptoms) leads to overcorrection. 1, 2 Overcorrection occurred in 2.3% of patients receiving targeted correction versus 1.4% with routine care in a recent trial. 10