Enzymes in benign and malignant effusions.

A critical review of the work done in this area indicates that, of the available enzyme systems now used in clinical diagnosis, the LDH system is the only one of significant value in the examination of pleural and peritoneal effusions. In terms of differential diagnosis, estimation of pleural or peritoneal fluid LDH levels will enable the examiner to distinguish between poorly cellular vs. abundantly cellular effusions. In the abundantly cellular effusions, estimation of levels of LDH do not distinguish with any degree of accuracy between those effusions due to inflammatory processes vs. neoplastic processes. Results of studies of LDH isoenzymes are at variance and require more study.