Serum lactate dehydrogenase isoenzyme 1. An early indicator of relapse in patients with testicular germ cell tumors.

The present study aimed to evaluate serum lactate dehydrogenase isoenzyme 1 (S-LD-1) as an indicator of relapse for patients with testicular germ cell tumors. Twenty-seven patients were investigated with repeated determinations of S-LD-1 from diagnosis to relapse; 9 had seminoma and 18 nonseminomatous tumors. Eleven of 21 had raised S-LD-1 at relapse (4 with seminoma). Seven of the 27 patients had a raised S-LD-1 for median 2 months (1.4-4.5 months) before relapse was detected. Thus, S-LD-1 is of use, complementary to clinical examinations, determinations of serum alpha fetoprotein and human chorionic gonadotropin, and CT scans, in monitoring patients with testicular germ cell tumors for relapse.