A 26-year-old pregnant woman presenting with repeated episodes of vaginal bleeding, weight loss, and shortness of breath was diagnosed with choriocarcinoma with metastases to both lungs. Chorionic gonadotropin levels (hCG) were >2.5 x 106mU/mL. Consistent with hCG-induced subclinical hyperthyroidism, she had a suppressed TSH of 0.037mU/L (0.49 – 4.67), a T4 of 18.1µg/dL (4.9 – 10.7), and T3 of 136ng/dL (45 – 137). Chemotherapy with a combined regimen with etoposide, methotrexate, and dactinomycine was started. The initial course was complicated […]