Lactic dehydrogenase isoenzymes in human bladder cancer.

The lactic dehydrogenase isoenzymic patterns of normal, atypical and neoplastic urothelium were studied. In comparison to normal, the atypical urothelium had a significant increase in the LDH-V/I ratio. In neoplastic urothelium the LDH-I per cent was increased in low grade tumors, while the LDH-V per cent and LDH-V/I ratio was increased in high grade tumors. The findings in high grade tumors are thought to represent altered genetic expression with activation of the gene locus controlling M subunit synthesis.