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CSF Composition — FRCA Primary MCQ

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HardPhysiology - NeurophysiologyCSF CompositionFRCA Primary

Which statement about normal cerebrospinal fluid composition is correct?

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Correct answer: B — CSF glucose is commonly about two-thirds of simultaneous plasma glucose

The best answer is “CSF glucose is commonly about two-thirds of simultaneous plasma glucose”. Normal CSF glucose is lower than plasma glucose, commonly around 60–70% of the simultaneous plasma concentration. CSF protein is markedly lower than plasma protein. Although approximately 500 mL of CSF may be produced daily, the total adult volume at any time is roughly 120–150 mL because production and reabsorption are continuous.

Reference: Royal College of Anaesthetists, Primary FRCA Syllabus 2021: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf