Serum lactate dehydrogenase and its isoenzymes in leukemia patients: possible role in diagnosis and treatment monitoring.

Serum levels of total LDH (T.LDH) and LDH isoenzymes in 145 untreated leukemia patients were examined and compared with those of 150 age and sex matched healthy individuals (controls) and 77 anemia patients (pathological controls). As compared to the controls, T.LDH, LDH-1, LDH-2, LDH-3, LDH-4 and LDH-5 values were significantly elevated (p < 0.001) in untreated leukemia patients. T.LDH, LDH-1, LDH-2 and LDH-3 levels were significantly raised in anemia patients as compared to the controls. A significant increase in the levels of T.LDH, LDH-2, LDH-3 and LDH-4 was observed in untreated leukemia patients as compared to the anemia patients. LDH-4 was most specific (81.0%), while LDH-2 was the most sensitive (84.0%) marker for leukemia. Mean values of all the markers were higher in leukemia patients with persistent leukemic activity/accelerated leukemic phase as compared to the patients in remission. Serum levels of T.LDH as well as all the five isoenzymes were significantly lower in leukemia patients in remission as compared to untreated leukemia patients. The study indicated that alterations in T.LDH and its isoenzymes are useful for diagnosis and treatment monitoring of leukemia.