Normal | Bacterial | Viral | Tuberculous | Fungal | |
Opening presssure (cm CSF) | 12–20 | Raised | Normal / mildly raised | Raised | Raised |
Appearance | Clear | Purulent, turbid, cloudy | Clear | Clear or cloudy | Clear or cloudy |
CSF WBC (cells/μL) | <5 | Raised (>100) b | Raised (5–1000) b | Raised (5–100) b | Raised (5–100) b |
Predominant cell | n/a | Neutrophils c | Lymphocytes d | Lymphocytes e | Lymphocytes |
CSF protein (g/L) | Raised | Mildly raised | Markedly raised | Raised | |
CSF plasma glucose ratio | >0.66 | Very low | Normal / slightly low | Very low | Low |
CSF glucose (mmol) | 2.6–4.5 | Very low | Normal / slightly low | Very low | Low |
Note: Local laboratory ranges for biochemical tests should be consulted. They may vary from the quoted values here. A traumatic lumbar puncture (LP) will affect the results by falsely elevating the white cells due to excessive red cells. A common correction factor used is 1:1000.
aDerived from Tom Solomon–Lecture Notes in Neurology
bOccasionally the CSF white cell count (WCC) may be very high (several thousand) in bacterial meningitis. Alternatively the CSF WCC may be normal (especially in immunodeficiency or tuberculous meningitis).
cMay be lymphocytic if antibiotics given before LP (partially treated bacterial meningitis),
or with certain bacteria, eg Listeria monocytogenes.
dMay be neutrophilic in enteroviral meningitis (especially early in disease).
eMay be neutrophilic early in the disease course.
CSF = cerebrospinal fluid; WBC = white blood cell count; WCC = white cell count