We describe a 26-year-old man with metastatic choriocarcinoma who presented with hyperthyroidism associated with elevated β-human chorionic gonadotropin (B-HCG) and respiratory failure secondary to diffuse lung metastasis. After the first cycle of chemotherapy, the concentration of B-HCG dramatically decreased and the patient became euthyroid, allowing us to discontinue antithyroid medications. The patient's hyperthyroidism was caused by stimulation of the thyroid gland by high B-HCG levels, as shown by the marked improvement of the patient's thyroid function panel after chemotherapy.H uman chorionic gonadotropin (HCG)-induced hyperthyroidism is a rare cause of hyperthyroidism. It is seen in patients suff ering from conditions associated with extremely high levels of HCG, such as hyperemesis gravidarum, hydatidiform moles, and germ cell tumors. At very high levels, HCG can stimulate the TSH receptor, causing hyperthyroidism (1). We present the case of a 26-year-old man diagnosed with metastatic choriocarcinoma and concomitant hyperthyroidism related to extremely high levels of β-human chorionic gonadotropin (B-HCG). Th e patient's hyperthyroidism resolved as the B-HCG decreased because of chemotherapy.
CASE DESCRIPTIONA previously healthy 26-year-old man presented with a 3-week history of fever, chills, cough, hemoptysis, and dyspnea. He also reported anxiety, palpitations, hand tremors, and a 30-pound weight loss in a 3-month period. A chest radiograph showed multiple diff use nodules of 1 to 3.5 cm throughout both lung fi elds (Figure 1). Upon presentation at our hospital, his heart rate was 136 beats per minute, and his respiratory rate was 25 breaths per minute. On initial exam he had fi ne crackles in both lung bases. Th e thyroid gland and scrotal examinations were unremarkable. His free thyroxine was 4.14 ng/dL (normal, 0.93-1.7); free triiodothyronine, 10.6 pg/mL (normal, 2.3-4.2); thyroid-stimulating hormone (TSH), <0.01 mcIU/mL (normal, 0.27-4.20); B-HCG, 616,433 MIU/mL (normal, 1-5); lactate dehydrogenase, 1232 IU/L (normal, 135-225); alanine aminotransferase, 53 IU/L (normal, 7-40); and aspartate aminotransferase, 61 IU/L (normal, 10-42). Th e patient was started on methimazole, dexamethasone, and propranolol. Testicular ultrasound showed a heterogeneous right testicle with microlithiasis and a 10 mm septated upper pole cyst, with moderate right hydrocele. Computed tomography (CT) of the head, chest (Figure 2), abdomen, and pelvis suggested diff use metastasis of the brain, lungs, liver, and retroperitoneal lymph nodes. CT-guided biopsy of one of the lung nodules was consistent with metastatic choriocarcinoma based on positive staining for B-HCG.Th e patient was treated with bleomycin, etoposide, and cisplatin. After completing his fi rst chemotherapy cycle, his serum B-HCG decreased signifi cantly and the thyroid function panel improved to near normalization (Table 1). Methimazole was decreased from 45 mg to 10 mg daily and was discontinued 3 weeks after he completed the fi rst cycle of chemotherapy...