Which CSF glucose pattern is typical of viral meningitis?

• A. Normal to slightly reduced CSF glucose.
• B. Low CSF glucose with high protein.
• C. CSF glucose markedly elevated.
• D. CSF glucose is always normal.

Answer: (A)

The main idea is how CSF glucose behaves in meningitis and what it tells you about the infectious agent. Glucose in CSF mainly mirrors what’s in the blood, diffusing across the blood–CSF barrier. In viral meningitis, the inflammation is milder and there’s less metabolic activity consuming glucose in the CSF, so the glucose level stays close to normal plasma levels—often normal, sometimes just a little lower. This contrasts with bacterial meningitis, where bacteria and inflammatory cells actively use glucose, and the barrier’s transport can be impaired, leading to a lower CSF glucose with higher protein and a neutrophilic cell count. A markedly elevated CSF glucose isn’t a feature of meningitis at all, since there’s no mechanism to raise CSF glucose above plasma levels, and saying it’s always normal is misleading because mild reductions can occur. So, normal to slightly reduced CSF glucose is the typical pattern for viral meningitis.