Glucose, Spinal Fluid
Glucose enters the spinal fluid from the plasma by both diffusion and active transport. The concentration and duration of plasma glucose influence the spinal fluid level. Typically, spinal fluid glucose concentration is 60 to 70% of plasma glucose and lags behind the plasma level by 30 to 90 minutes. An increase in spinal fluid glucose means the patient was hyperglycemic 30 to 90 minutes before and is not clinically significant. Spinal fluid glucose may be decreased by bacterial, fungal, and mycobacterial meningitis; primary and metastatic cancer, subarachnoid hemorrhage; and hypoglycemia. Spinal fluid glucose is decreased in 60 to 80% of bacterial meningitis cases. Viral meningitis and neurosyphilis usually do not affect spinal fluid glucose concentration.
Reference range is 40 to 80 mg/dL.
Specimen requirement is 1 mL of spinal fluid.
