Cerebrospinal Fluid Analysis Guidelines

Normal Reference Values

The normal cerebrospinal fluid glucose level ranges from 2.6-4.5 mmol/L, with a CSF-to-plasma glucose ratio of >0.66, and protein is <0.4 g/L, according to the Journal of Infection 1, 2, 3
Normal CSF glucose is approximately two-thirds (66%) of plasma glucose, as reported by the Journal of Infection 2, 4
The CSF white cell count is typically <5 cells/μL, as stated in the Journal of Infection 1, 2

A CSF/plasma glucose ratio <0.36 has 93% sensitivity and specificity for bacterial meningitis, with absolute CSF glucose typically <2.6 mmol/L, according to the Journal of Infection 2, 3
In bacterial meningitis, CSF protein is typically >2.2 g/L (>220 mg/dL), as reported by Critical Care Medicine 7
For viral meningitis, the CSF/plasma glucose ratio remains normal or slightly low but stays >0.36, with CSF protein mildly elevated, as stated by the Journal of Infection and Praxis Medical Insights 1, 5, 6

A CSF glucose >2.6 mmol/L makes bacterial meningitis unlikely, but this threshold becomes unreliable in patients with hyperglycemia or abnormal glucose metabolism, according to the Journal of Infection and Praxis Medical Insights 2, 3, 5
A CSF protein <0.6 g/L essentially excludes bacterial meningitis, making this a useful negative predictor, as reported by the Journal of Infection and Praxis Medical Insights 1, 2, 6