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Interpretation of CSF results from lumbar puncture (LP)

 

  • The outline below gives basic indication of patterns of disease to look for in CSF. However, note that CSF results should always be interpreted with the clinical picture in mind.
    • Reference ranges may vary between labs

 

Normal results in adults

  • Appearance: Clear
  • Opening pressure: 10-20 cmCSF
  • WBC count: 0-5 cells/µL
    • < 2 polymorphonucleocytes [PMN])
    • Normal cell counts do not rule out meningitis or any other pathology
  • Glucose level: >60% of serum glucose
  • Protein level: < 45 mg/dL
  • Consider additional tests: CSF culture, others depending on clinical findings

 

Bacterial meningitis

  • Appearance: Clear, cloudy, or purulent
  • Opening pressure: Usually elevated (>25 cmCSF)
  • WBC count: >100 cells/µL
    • >90% PMN
    • Partially treated cases may have as low as 1 WBC/µL
  • Glucose level: Low (< 40% of serum glucose)
  • Protein level: Elevated (>50 mg/dL)
  • Additional tests: CSF Gram stain and cultures, blood cultures, CSF bacterial antigens, CSF polymerase chain reaction (PCR) for common viruses

 

Viral meningitis

  • Appearance: Clear
  • Opening pressure: Normal or elevated
  • WBC count: 10-1000 cells/µL
    • Classically lymphocytes but may be PMN early
  • Glucose level: >60% serum glucose (may be low in HSV infection)
  • Protein level: Elevated (>50 mg/dL)
  • Consider additional tests: CSF Gram stain and cultures, blood cultures, CSF bacterial antigens, CSF PCR for herpes simplex virus (HSV), varicella-zoster virus (VZV) and other common virus such as adenovirus or enterovirus depending on area

 

Fungal meningitis

  • Appearance: Clear or cloudy
  • Opening pressure: Elevated
  • WBC count: 10-500 cells/µL
  • Glucose level: Low
  • Protein level: Elevated
  • Additional tests: CSF Gram stain and cultures, blood cultures, CSF bacterial antigens, CSF PCR, CSF India ink

 

Tuberculosis (TB)

  • Appearance: Clear or opaque
  • Opening pressure: Elevated
  • WBC count: 50-500 cells/µL
    • Early PMNs then lymphocytes
  • Glucose level: Low
  • Protein level: Elevated
  • Consider additional tests: CSF Gram stain and cultures, blood cultures, CSF bacterial antigens, CSF PCR, CSF tuberculosis culture/stain looking for acid fast bacilli (AFB)

 

Subarachnoid hemorrhage (SAH)

  • Appearance: Xanthochromia, bloody, or clear
  • Opening pressure: Elevated
  • WBC count: (1 additional WBC per 1000 RBCs is considered normal correction)
  • Glucose level: Normal
  • Protein level: Elevated
  • Additional tests: CSF Gram stain and culture, photospectometry to examine for xanthochromia

 

Multiple sclerosis (MS)

  • Appearance: Clear
  • Opening pressure: Normal
  • WBC count: 0-20 cells/µL (lymphocytes)
  • Glucose level: Normal
  • Protein level: Usually mildly elevated (45-75 mg/dL)
  • Additional tests: Oligoclonal bands (paired serum and CSF)

 

Guillain Barré syndrome (GBS)

  • Appearance: Clear or xanthochromia
  • Opening pressure: Normal or elevated
  • WBC count: Normal or elevated
  • Glucose level: Normal
  • Protein level: Elevated