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Table 123.4

Cerebrospinal Fluid (CSF) Formulae in Meningitis and Encephalitis

PyogenicViralTuberculousCryptococcalViral
Elementmeningitismeningitismeningitismeningitisencephalitis
White cell count/mm3>1000<500<500<150<250
Predominant cell typePolymorphsLymphocytesLymphocytesLymphocytesLymphocytes
Protein concentration (g/L)>1.50.5–1.01.0–5.00.5–1.00.5–1.0
CSF: blood glucose<50%>50%<50%<50%>50%

  • The values given are typical, but many exceptions occur
  • Red cells may be seen in the CSF in herpes encephalitis, reflecting cerebral necrosis
  • Antibiotic therapy substantially changes the CSF formula in pyogenic bacterial meningitis, leading to a fall in cell count, increased proportion of lymphocytes and fall in protein level. However, the low CSF glucose level usually persists.