CSF-serum glucose ratio
The ratio of cerebrospinal fluid glucose to simultaneous serum glucose, used to assess CNS metabolism and infection.
Full Definition
The CSF-serum glucose ratio is a calculated parameter that compares the glucose concentration in cerebrospinal fluid to the simultaneous serum glucose level, normally maintained at approximately 0.6 (60%). This ratio accounts for variations in serum glucose and provides a more accurate assessment of CNS glucose transport and metabolism than absolute CSF glucose values alone. In neuroimmunological conditions, particularly infectious or inflammatory processes, this ratio may be decreased due to increased glucose consumption by inflammatory cells or impaired glucose transport across the blood-brain barrier. The ratio is essential for distinguishing between different causes of CNS inflammation and monitoring treatment response.
Usage
Usage note: Always express as decimal ratio; normal range typically 0.5-0.7.
In Context
- "The CSF-serum glucose ratio of 0.35 suggested bacterial meningitis rather than viral encephalitis." — Emergency department report
- "Normal CSF-serum glucose ratio helped exclude infectious causes of meningoencephalitis." — Diagnostic workup