Changes in lactate dehydrogenase isoenzyme patterns in patients with tumours of the central nervous system.?

The total activities of lactate dehydrogenase (LD) and the LD isoenzyme distribution were determined on homogenates from 61 benign and malignant intracranial tumours, and in serum and cerebrospinal fluid from 45 and 28 of the tumour patients respectively. The LD activity and the LD isoenzyme distribution in serum were not changed in patients with intracranial tumours. The LD activity in the cerebrospinal fluid was raised in about 50% of the tumour patients, but without any significant differences between patients with benign and malignant tumours. Except for very low activities in acoustic schwannomas and in pituitary adenomas, the tumour tissue did not differ significantly from normal brain in total LD activity. The LD isoenzyme distribution showed a pronounced cathodal shift in the grade 3-4 astrocytomas and the metastatic carcinomas, but an anodal shift in the grade 1-2 astrocytomas and the oligodendrogliomas. The meningiomas and the ocoustic schwannomas showed a midzone isoenzyme pattern with a dominant LD3 fraction. Knowledge of the LD isoenyme distribution can thus sometimes be a complement to the histological examination in the classification of brain tumours.