Cerebrospinal-fluid lactic dehydrogenase and its isoenzymes in infections of the central nervous system.

Abstract

Twenty-four of 25 patients with bacterial meningitis and nine of 11 with CNS viral infection had increased LDH activity in the CSF. The mean levels were 112.8 units per milliliter in bacterial, 193 units in pneumococcal and 23 units in meningococcal meningitis, and 22.6 units per milliliter in viral infections. In the CSF of patients with bacterial infection isoenzyme fractions 4 and 5 were preponderant, suggesting that the enzyme was derived from granulocytes, because normal CSF, serum and brain tissue have an isoenzyme pattern characterized by a predominance of LDH 1 and 2. In viral infections of the CNS, the mild elevations in LDH were due to fractions 1 and 2, but not 4 and 5. In contrast, patients who died with either bacterial or viral CNS infection had levels of LDH 1 and 2 over 50 units per milliliter, suggesting extensive CNS damage.