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PTD - 340

Test Directory - CSF Glucose

Clinical Indications

The CSF glucose concentration may be altered in a variety of pathologic conditions. Abnormally low CSF glucose concentrations can occur in bacterial meningitis and mycobacterial, mycoplasmal, and fungal CNS infections.

Request Form 

Combined Pathology Blood form (Yellow/Black)

Availability

On request

Specific Criteria

None.

Patient Preparation

None required.

Limitations

 

It normally takes several hours for the serum glucose to equilibrate with the CSF glucose.

Turnaround Time

Same day

Specimen

CSF

Volume

Minimum of 0.5 ml.

Container

CSF within a grey top (fluoride) tube

Causes for Rejection

Unlabelled sample.

Reference Range

The normal CSF-to-serum glucose ratio is approximately 0.6; ventricular CSF has a higher glucose concentration than CSF in the lumbar space by 0.33 to 1.0 mmol/L

Reference: Fishman RA.Studies of the transport of sugars between blood and CSF in normal states and in meningeal carcinomas. Trans Am Neurol Assoc. 1963;88:114.

Interpretation

CSF glucose concentration may be altered in a variety of pathologic conditions. Abnormally low CSF glucose concentrations can occur in bacterial meningitis and mycobacterial, mycoplasmal, and fungal CNS infections. During recovery from meningitis, CSF glucose concentration tends to normalize more rapidly than do the CSF cell count and protein concentration.

The CSF glucose concentration is typically normal during most viral CNS infections, although exceptions have been reported in patients with meningoencephalitis due to mumps, choriomeningitis (LCM), enteroviruses, lymphocytic , herpes simplex, and herpes zoster viruses.

Low CSF glucose concentrations can also be observed in CNS infections due to M. pneumoniae and noninfectious processes, including malignant processes infiltrating the meninges, subarachnoid hemorrhage, and in CNS sarcoidosis. However, CSF glucose concentrations less than 1.0 mmol/L are strongly predictive of bacterial meningitis.

The CSF-to-serum glucose ratio has limited utility in neonates and in patients with severe hyperglycemia. CSF glucose levels rarely exceed 300 mg/dL (16.7 mmol/L) even in patients with severe hyperglycemia

Lab. Handling

Processing: Centrifuge grey top (fluoride) tube and aliquot into a false bottom tube with a 3-prefix barcode on line 1 of the Cobas analyser. Store at 4C in the cold room (CB23) after analysis.

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Version 1.1 / June 2015                                                                                                          Approved by: Consultant Biochemist