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Stability of cerebrospinal fluid/serum glucose ratio and cerebrospinal fluid lactate concentrations over 24 h: analysis of repeated measurements

Irena Dujmovic and Florian Deisenhammer

Abstract

Background: The cerebrospinal fluid/serum glucose ratio (CSF/Sglu) and CSF lactate measurements are part of the routine CSF work-up. The in-vitro stability of both metabolites in CSF has not been formally investigated.

Methods: Following collection, CSF/Sglu and CSF L-lactate concentrations were measured repeatedly at five time points (baseline, 1 h, 2 h, 4 h and 24 h) in CSF and whole blood specimens stored at 4°C.

Results: CSF glucose and lactate concentrations were stable over 24 h in samples with both normal and increased CSF cell counts. The CSF cell count did not influence CSF glucose concentrations, but correlated significantly with CSF lactate concentrations. The CSF/Sglu increased significantly over time due to glucose consumption.

Conclusions: Glucose and L-lactate are stable in CSF specimens at 4°C over 24 h. The CSF/Sglu seems to be more reliable than CSF lactate because it is independent of the cell count. Falsely increased CSF/Sglu may be corrected by the rate of consumption of blood glucose.

Clin Chem Lab Med 2010;48:209–12.


Corresponding author: Prof. Florian Deisenhammer, MD, MSc, Neuroimmunology Laboratory, Innsbruck Medical University, Anichstr. 35, 6020 Innsbruck, Austria Phone: +43 512 504 24264, Fax: +43 512 504 6724231,

Received: 2009-8-14
Accepted: 2009-9-24
Published Online: 2009-12-04
Published in Print: 2010-02-01

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