Glucose, Cerebrospinal Fluid (CSF)


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Subject: Glucose, Cerebrospinal Fluid (CSF)

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  • Glucose in the CSF is about two thirds of the serum glucose measured during the preceding 2–4 hours in normal adults. This ratio decreases with increasing serum glucose levels. CSF glucose levels generally do not go above 300 mg/dL regardless of serum levels. Critical values are <30 mg/dL. Glucose in the CSF of neonates varies much more than that in adults, and the CSF-to-serum ratio is generally higher than in adults.

  • Normal range: 50–80 mg/dL.


  • Diagnosis of tumors, infections, inflammation of the CNS, and other neurologic and medical conditions.


Increased In

  • Elevated levels of glucose in the blood

  • CNS syphilis

Decreased In

  • CNS infections (glucose levels are usually normal in viral infections)

  • Chemical meningitis

  • TB meningitis

  • Cryptococcal meningitis

  • Mumps

  • Primary and metastatic tumors of meninges

  • Sarcoidosis

  • Inflammatory conditions

  • Subarachnoid hemorrhage

  • Hypoglycemia


  • Normal glucose levels do not rule out infection because up to 50% of patients who have bacterial meningitis have normal CSF glucose levels.