Clinical significance and source of raised catalytic activities of phosphohexose isomerase in the CSF in meningitis.

The value of phosphohexose isomerase (EC 5.3.1.9) determination in the CSF in the diagnosis of meningitis was tested under routine conditions. In 48 patients with untreated bacterial meningitis, enzyme activity concentrations between 40 and 2335 U/l were measured, whereas the highest phosphohexose isomerase activity concentration in 92 patients with viral meningitis was 34 U/l. Lysis of the CSF leukocytes with Triton X-100 resulted in a substantial increase of phosphohexose isomerase activity. In bacterial meningitis these values increased to 200 to 7000 U/l, but remained under 150 U/l in viral meningitis. The raised enzyme activities are derived from the leukocytes and appear to reflect their functional and metabolic state. The information provided by the leukocyte morphology can thus be appreciably extended by phosphohexose isomerase determination.