Discordant human chorionic gonadotropin results giving rise to inappropriate therapy in a case of testicular cancer.

The most widely cited cause of a falsely elevated human chorionic gonadotropin level in patients with germ cell tumors is an elevated level of partially cross-reacting luteinizing hormone. Other causes of discordant human chorionic gonadotropin results (human chorionic gonadotropin elevated in 1 assay but normal in others) in testicular cancer have received scant attention. A patient with pure seminoma was given inappropriate chemotherapy on the basis of an elevated human chorionic gonadotropin level, later shown to be due to a nonspecific serum interfering substance. A discordant human chorionic gonadotropin result should be suspected when the human chorionic gonadotropin is only modestly elevated, there is no serial increase in the human chorionic gonadotropin level and no other evidence of tumor can be found.