False positive result of beta subunit of hCG testing in a patient with stage IA testicular germ cell tumor during routine follow-up

Abstract

Serum tumor markers: alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (beta-hCG), and lactase dehydrogenase (LDH) play an important role in the staging and monitoring of germ cell tumors. We report a case of a patient diagnosed with stage IA testicular nonseminoma. After orchidectomy patient was routinely followed with monthly AFP, beta-HCG, and LDH measurement. CT of abdomen and chest were performed. In ninth month of follow up, elevation of the beta subunit of hCG was found. The patient was diagnosed with biochemical relapse because of elevated HCG level with the absence of metastases in CT of chest, pelvis and abdomen. After questioning about cannabinoids use he admitted to smoking marihuana prior to blood testing. Repeated test showed normalization of the HCG value. Previously elevated HCG level was assumed as false-positive. He was spared unnecessary chemotherapy. This case highlights the need for interpreting tumor-marker elevations with caution.Querying patients about marijuana use and retesting hCG levels after a period of abstinence from cannabinoids is strongly recommended.