Cerebrospinal fluid lactate and pyruvate concentrations and their ratio

Objectives: Determinations of cerebrospinal fluid (CSF) lactate and pyruvate concentrations and CSF lactate:pyruvate (LIP) ratios are important in several clinical settings, yet published normative data have significant limitations. We sought to determine a large dataset of stringently-defined normative data for CSF lactate and pyruvate concentrations and CSF L/P ratios. Design and methods: We evaluated data from 627 patients who had determinations of CSF lactate and/or CSF pyruvate from 2001 to 2011 at the Cleveland Clinic. Inclusion in the normal reference population required normal CSF cell counts, glucose and protein and routine serum chemistries and absence of progressive brain disorder, epilepsy, or seizure within 24 h. Brain MRI, if done, showed no evidence of tumor, acute changes or basal ganglia abnormality. CSF cytology, CSF alanine and immunoglobulin levels, and oligoclonal band analysis were required to be normal, if done. Various inclusion/exclusion criteria were compared. Results: 92 patients fulfilled inclusion/exclusion criteria for a reference population. The 95% central intervals (2.5%-97.5%) for CSF lactate and pyruvate levels were 1.01-2.09 mM and 0.03-0.15 mM, respectively, and 9.05-26.37 for CSF L/P. There were no significant gender-related differences of CSF lactate or pyruvate concentrations or of CSF LIP. Weak positive correlations between the concentration of CSF lactate or pyruvate and age were noted. Conclusions: Using stringent inclusion/exclusion criteria, we determined normative data for CSF lactate and pyruvate concentrations and CSF L/P ratios in a large, well-characterized reference population. Normalcy of routine CSF and blood analytes are the most important parameters in determining reference intervals for CSF lactate and pyruvate. (C) 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.