Lactate dehydrogenase isoenzymes in tumours of the nervous system

Summary The variations in the isoenzymes of lactic acid dehydrogenase have been studied in a series of tumours of the nervous system. From these the ratio of heart muscle component to skeletal muscle component (the H/M ratio) has been calculated and compared with the H/M ratio of a variety of regions of normal brain. Oligodendrogliomata were found to have a very high H/M ratio. There was a decrease in the ratio with increasing degrees of de-differentiation of all tumours studied. However the H/M ratio does not appear directly related to the rate of growth irrespective of the tissue of origin of the tumour. Tumours derived from different tissues appear to have their own range of ratios. Tumour cyst fluids showed similar ratios to their parent tumours.