Phosphohexose isomerase in cerebrospinal fluid in meningitis.

The diagnostic value of determining phosphohexose isomerase (PHI, E.C. 5.3.1.9) activity in the CSF for differential diagnosis of bacterial and viral meningitis was investigated. In 29 patients with untreated bacterial meningitis, a mean enzyme activity of 511 U/1 was found, whereas a value 19 U/1 was found in 61 cases of viral meningitis. The reference range with an upper limit of 6 U/1 was determined from CSF samples from 163 "healthy" children. The high diagnostic sensitivity and specificity of 100% and 99.5% respectively make PHI a sensitive differential diagnostic parameter in meningitis.