[Significance of lactate level, lysozyme concentration and phosphohexose isomerase activity in the cerebrospinal fluid in the differential diagnosis of meningitis].

The significance of the measurement of lactate, lysozyme and PHI in CSF for differential diagnosis of meningitis was examined in 58 cases of viral, 36 of bacterial and 5 of tuberculous etiology. In the early phase of the illness CSF lactate was found to be the most sensitive parameter for distinction of viral from bacterial or tuberculous meningitis respectively. Except for one case CSF lactate exceeded 3.8 mmol/l in all cases of bacterial etiology, whereas this value was never reached in any case of viral meningitis. While lactate concentration was maximal on the day of admission and declined continuously thereafter, PHI activity reached its maximum on the third day after beginning of the therapy. At this time all patients with a bacterial or tuberculous meningitis had PHI activities about 50 U/l. This value wasn't exceeded in any case of viral meningitis. In a few cases some days after onset of therapy a distinction of bacterial meningitis from viral forms was still possible by PHI determination but not by lactate measurement. Determination of lysozyme also could be helpful in the later phase of the disease.