Serum lactate dehydrogenase isoenzyme pattern in non-Hodgkin's lymphomas

Serum lactate dehydrogenase (S-LDH) and its isoenzyme pattern were assayed in 63 non-Hodgkin's lymphoma (NHL) patients, 37 at diagnosis, 15 at relapse and 11 in complete remission (CR). S-LDH in NHL patients with active disease was higher than in normal subjects and CR patients (p less than 0.001). Among the isoenzymes, LDH-2 and LDH-5 showed no remarked differences; LDH-1 was reduced and LDH-3 and LDH-4 raised in comparison to the normal group (p less than 0.001). S-LDH levels and isoenzymes 1 and 4 were influenced by the stage, the histological subgroup and by the presence of general symptoms. In fact, cases in stage IV, with "high-grade malignancy" and with general symptoms, had higher S-LDH levels and more evident LDH-1 and LDH-4 changes than the other stages, the other histopathological subgroups and the cases classified as "A". S-LDH was the same as in normal subjects in the "low-grade" and "intermediate-grade" malignancies as was LDH-1 in stage II and LDH-4 in stages II and III, in "low-grade" malignancy and in the A cases. In contrast, LDH-3 was always high, with no significant difference in relation to the variables considered. Thus, in NHL, LDH-3 seems to be a reliable marker of the presence of the disease in any case, whereas S-LDH is more related to the spread of the lymphoma.