Role of lactate dehydrogenase isoenzymes in testicular cancer.

Changes in the serum levels of lactate dehydrogenase have been noted to reflect growth and/or regression in many patients with testicular tumors, but they were nonspecific. However, elevation of the first of the LDH isoenzymes (LD-1) has been found specific to testicular cancer among all neoplasms. In this prospective preliminary report of 19 testicular cancer patients serum LD-1 was found to be normal in 4 patients with no tumor present. Therefore, there were no false positive findings. Of 6 patients with microscopic disease, LD-1 level was normal. Of 9 patients with gross disease, 5 had elevated serum LD-1 and 4 had normal LD-1. Of 4 patients with seminoma, 3 had elevated LD-1 while all 4 patients had no other elevated markers. It appears that elevation of serum LD-1 provides a marker for seminoma and a marker with some specificity for testicular cancer.