Lactate dehydrogenase as a marker for testicular germ-cell tumours.

One hundred and eighty-four patients with testicular germ-cell tumours, 92 with seminoma and 92 with non-seminomatous germ-cell tumours (NSGCT) had total lactate dehydrogenase (LD) assay performed at the time of initial staging following orchidectomy. The proportion of patients with elevated plasma LD and the mean plasma LD increased with advancing stage and increasing tumour bulk for both seminoma and NSGCT. Of patients receiving cytotoxic chemotherapy, 87.5% with seminoma and 63% with NSGCT had elevated plasma LD with subsequent levels reflecting regression or progression of disease. Elevated plasma LD levels were seen in four of seven seminoma, and in 18 of 30 NSGCT patients relapsing after primary treatment. The LD assay provides useful information, and complements the routine measurement of alphafetoprotein (AFP) and beta human chorionic gonadotrophin (beta hCG) in the management of patients with testicular germ-cell tumours.