Lactic acid in cerebrospinal fluid: evaluation and application of an automated enzymatic assay

The DuPont ACA lactic acid procedure was evaluated for use on cerebrospinal fluid (CSF). The method was linear to at least 13.9 mmol per L, day-to-day precision ranged from 3 to 9 percent (CV), and recovery of lactate added to cerebrospinal fluid averaged 104 percent. The method correlated closely with a centrifugal analyzer procedure; r = 0.996, SEy,x 0.16 mmol per L. The reference range, based on patient CSF samples, was 0.8 to 2.3 mmol per L. Elevated CSF lactate concentrations were found in patients with bacterial, but not viral, meningitis. Less marked elevations occurred with head trauma, seizures, strokes, or hemorrhage in the central nervous system. The results suggest that this method is useful in the early diagnosis of bacterial meningitis.