Serum glucose adjusted cut-off values for normal cerebrospinal fluid/serum glucose ratio: implications for clinical practice
H Hegen, M Auer, F Deisenhammer - Clinical Chemistry and …, 2014 - degruyter.com
H Hegen, M Auer, F Deisenhammer
Clinical Chemistry and Laboratory Medicine (CCLM), 2014•degruyter.comBackground: Calculation of the cerebrospinal fluid/serum glucose (CSF/SGlu) ratio is part of
the routine CSF work-up, however, different cut-off values ranging from 0.3 to 0.5 have been
suggested so far to distinguish physiological from pathological conditions. The objective of
this study was to determine cut-off values for normal CSF/SGlu ratio dependent on serum
glucose concentrations. Methods: We screened our database for paired CSF and serum
samples, which have been collected by lumbar puncture, were processed within 1 h after …
the routine CSF work-up, however, different cut-off values ranging from 0.3 to 0.5 have been
suggested so far to distinguish physiological from pathological conditions. The objective of
this study was to determine cut-off values for normal CSF/SGlu ratio dependent on serum
glucose concentrations. Methods: We screened our database for paired CSF and serum
samples, which have been collected by lumbar puncture, were processed within 1 h after …
Abstract
Background: Calculation of the cerebrospinal fluid/serum glucose (CSF/SGlu) ratio is part of the routine CSF work-up, however, different cut-off values ranging from 0.3 to 0.5 have been suggested so far to distinguish physiological from pathological conditions. The objective of this study was to determine cut-off values for normal CSF/SGlu ratio dependent on serum glucose concentrations.
Methods: We screened our database for paired CSF and serum samples, which have been collected by lumbar puncture, were processed within 1 h after withdrawal, showed cell count <15/3, erythrocyte count <1500/3 and normal CSF total protein resulting in 1036 sample pairs. Glucose concentrations in CSF and serum were measured by enzymatic spectrophotometry.
Results: Median glucose concentration in CSF was approximately 60% of that in serum. CSF/SGlu ratios negatively correlated with serum glucose levels (R=–0.586, p<0.001) and cut-off values for normal CSF/SGlu ratio defined as the 5th percentile were 0.5 for patients with serum glucose concentrations <100 mg/dL, 0.4 for those with a glucose level of 100–149 mg/dL and 0.3 for serum glucose concentrations ≥150 mg/dL.
Conclusions: CSF/SGlu ratio inversely correlates with serum glucose concentrations in a non-linear manner. These findings suggest that cut-off values for normal CSF/SGlu ratio must be adjusted to serum glucose levels, probably explaining the considerably varying cut-offs that have been reported so far.
De Gruyter