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Sodium Correction Rate — SCE Medical Oncology MCQ

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ModerateOncological EmergenciesSodium Correction RateSCE Medical Oncology

A 58-year-old woman with cancer develops acute confusion and is found to have a serum sodium of 116 mmol/L. SIADH from her SCLC is confirmed. She is mildly symptomatic (headache, nausea). What is the maximum rate of sodium correction in the first 24 hours?

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Correct answer: D — Maximum 10 mmol/L per 24 hours (some guidelines suggest ≤8 mmol/L) — overcorrection risks osmotic demyelination syndrome (ODS/central pontine myelinolysis), a devastating neurological complication

Hyponatraemia correction must be carefully controlled to prevent osmotic demyelination syndrome (ODS): target correction ≤10 mmol/L per 24 hours (conservative guidelines: ≤8 mmol/L per 24 hours; ≤18 mmol/L per 48 hours). For symptomatic severe hyponatraemia (seizures, reduced GCS), initial rapid correction with 100-150 mL 3% hypertonic saline bolus (raise Na by 1-2 mmol/L per hour for first 4-6 hours) is appropriate, but subsequent correction must slow down. Frequent Na monitoring (every 2-4 hours initially) guides management. Desmopressin 'clamp' can be used to prevent overcorrection.

Reference: NICE; ESMO Oncological Emergencies; Sterns et al NEJM 2015