A 40-year-old post-laparotomy patient has a serum sodium of 128 mEq/L on day 2. The resident plans aggressive sodium correction. The maximum safe rate of correction for symptomatic hyponatraemia to prevent osmotic demyelination syndrome (ODS) is:
- A 20 mEq/L in 24 hours
- B 5 mEq/L in 24 hours
- C 10–12 mEq/L in 24 hours and < 18 mEq/L in 48 hours ✓
- D Rapid correction of 2–3 mEq/L per hour is safe for up to 24 hours
Correct answer: C. 10–12 mEq/L in 24 hours and < 18 mEq/L in 48 hours
Explanation
Overly rapid correction of chronic hyponatraemia risks osmotic demyelination syndrome (pontine myelinolysis). Current guidelines recommend a maximum correction rate of 10–12 mEq/L per 24 hours and not more than 18 mEq/L per 48 hours. In severe symptomatic hyponatraemia (seizures, obtundation), an initial rapid correction of 1–2 mEq/L/hour for the first 3–4 hours is permissible to relieve cerebral oedema, but the 24-hour ceiling still applies. Rapid persistent correction above 12 mEq/L/day causes irreversible neurological injury.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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