Physiology Nervous system 5ff2032e Glucose in CSF A 1/3 of blood glucose B 1/2 of blood glucose C 2/3 of blood glucose D None High-Yield Explanation Glucose level in CSF: 64mg/dL Plasma: 100mg/dL CSF/Plasma ratio turns out to be: 0.64 Which is closer to 2/3=0.66 Ref:Ganongs Review of medical physiology;23 rd edition ; pg : 571 ; table 34-2.