Normal Sodium 135-145 — FRCA Primary MCQ

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EasyPhysiology - Endocrine & MetabolicNormal Sodium 135-145FRCA Primary

The normal plasma sodium concentration is:

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Correct answer: D — 135-145 mmol/L

Normal plasma Na+ is 135-145 mmol/L. It is the major determinant of serum osmolality. Hyponatraemia (<135) can cause cerebral oedema / seizures / and death. Rapid correction risks central pontine myelinolysis (osmotic demyelination syndrome). Hypernatraemia (>145) causes cellular dehydration.

Reference: Power Kam 2018 Principles of Physiology for the Anaesthetist