CSF lactate in diseases of the CNS

The usefulness of the CSF lactate concentration in the diagnosis of bacterial meningitis was studied in 109 adults and children with a variety of infectious and neurologic diseases. A positive correlation was found between elevated lactate levels and the presence of leukocytes in the CSF. Elevations of the CSF lactate concentration with concomitantly negative Gram's stains and cultures were found in patients with infections at anatomic sites other than the CNS, accidental or neurosurgical head trauma, subarachnoid hemorrhage, and seizures due to alcoholism. When performed routinely on CSF, the positive predictive value was 31%, indicating that a diagnosis other than bacterial meningitis is more likely. We conclude that the CSF lactate concentration does not contribute to the diagnosis in children or adults with suspected meningitis.