Cerebrospinal fluid parameters for different aetiologies of meningitis1
| Normal | Bacterial | Viral | Tuberculous | Fungal | |
|---|---|---|---|---|---|
| Opening pressure, cm CSF | 12–20 | Raised | Normal / mildly raised | Raised | Raised |
| Appearance | Clear | Turbid, cloudy, purulent | Clear | Clear or cloudy | Clear or cloudy |
| CSF WCC, cells/μL | <5 | Raised (usually >100)a | Raised (usually 5–1,000)a | Raised (usually 5–500)a | Raised (usually 5–500)a |
| Predominant cell type | n/a | Neutrophilsb | Lymphocytesc | Lymphocytesd | Lymphocytes |
| CSF protein, g/L | <0.4 | Raised | Mildly raised | Markedly raised | Raised |
| CSF glucose, mmol | 2.6–4.5 | Very low | Normal / slightly low | Very low | Low |
| CSF:plasma glucose ratio | >0.66 | Very low | Normal / slightly low | Very low | Low |
Consult local laboratory values that may vary. A traumatic lumbar puncture may falsely elevate the white cell count, a correction factor of 1:1,000 white cells to red cells is often used.
↵aOccasionally the cerebrospinal fluid white cell count may be normal (especially in children and the immunocompromised).
↵bMay be lymphocytic if antibiotics given before lumbar puncture or with certain bacteria, eg Listeria monocytogenes.
↵cMay be neutrophilic in enteroviral meningitis.
↵dMay be neutrophilic early in the course of disease. CSF = cerebrospinal fluid; WCC = white cell count. Reproduced with permission from McGill F, Heyderman RS, Michael BD et al. The UK Joint Specialist Societies Guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults. J Infect 2016;72:405–38 under CC BY-NC-ND 4.0 licence.