Paraneoplastic Hyperthyroidism Secondary to a Chemotherapy-Induced Surge in β-hCG in a Patient with Non-Seminomatous Germ Cell Tumor.

Thyrotoxicosis as the presenting syndrome of an underlying β-hCG-secreting malignancy is well described. It has been previously theorized, but not reported, that the surge of β-hCG secondary to chemotherapy induction may inadvertently trigger thyrotoxicosis. After thorough review, this is the first documented case of such event in peer-reviewed medical literature published in the English language. This is a case of a 21-year-old male with stage IIIc non-seminomatous germ cell tumor who developed paraneoplastic hyperthyroidism within 4 days of the first cycle of chemotherapy. Management considerations are suggested based on this case and review of the literature.