Lactate dehydrogenase levels in cellular extracts of human malignant lymphomas.

Serum lactate dehydrogenase (LDH) levels have been claimed as an independent prognostic factor in non-Hodgkin's lymphomas (NHL). In the present study, the intracellular and serum LDH levels in Hodgkin's (HD) and NHL were investigated. We found that among NHL, the histologic types of high-grade malignancy (lymphoblastic, immunoblastic and centroblastic), according to the Kiel classification, have a significantly higher intracellular (p less than 0.01) and serum (p less than 0.05) content of this enzyme than those of low-grade malignancy. This finding could explain in part the relation between high serum LDH levels and poor prognosis. It is also possible that the stage of the disease at the moment of the serum determination could be related to the serum LDH level, because a large tumor burden is likely to release more enzyme than a smaller one. However, we could not test this hypothesis because in our series there was ony one NHL patient with stage I or II. Serum LDH level could be a predictor of prognosis in NHL because of its relationship with more malignant histological types, and possibly with more advanced diseases.