BMJ Case Reports 2011; doi:10.1136/bcr.04.2011.4163 1 of 3 BACKGROUND Hyperthyroidism is a common condition, but human cho-rionic gonadotrophin (HCG)-induced hyperthyroidism is rare. It can occur in patients with hyperemesis gravidarum, hydatidiform moles or germ cell tumours. Patients with HCG-induced hyperthyroidism have suppressed thyroid stimulating hormone (TSH) levels and elevated free thyroid hormones (FT4 and FT3), but typically lack clinical charac-teristics of Graves’ disease and TSH receptor antibodies. It is important to consider HCG-induced hyperthyroidism in patients presenting with biochemical hyperthyroidism but with an atypical clinical presentation. CASE PRESENTATION A 31-year-old man presented to the emergency department because of a headache of 7 days duration. He reported hav-ing coughed up a small amount of blood that day. He had noticed diarrhoea and had vomited once 2 days ago. On further questioning, the patient stated he had sweated slightly more during the past few days. He denied palpita-tions, irritability, tremor, visual problems or throat ache. His height was 166 cm and weight 68 kg. He had inten-tionally lost 10 kg during the past months with daily body building. He reported having felt well and physically fi t during the previous weeks. He did not take any drugs and his medical as well as family history were unremarkable. INVESTIGATIONS On examination, he appeared comfortable. Temperature was 36.6°C, blood pressure 120/60 mm Hg, the pulse 100 beats per min and the oxygen saturation 97% while he was breathing ambient air. The abdomen was tender on palpation, the remainder of the examination was normal. The neck was supple with no palpable masses or thyroid enlargement, there were no signs of ophthalmopathy. A radiograph of the chest showed multiple pulmonary nodules. CT of the chest and abdomen showed multiple bilateral pulmonary nodules. There were no pulmonary inf i ltrates or enlarged lymph nodes. A retroperitoneal mass of 5.7 x 4.3 cm in diameter was visible along the inferior vena cava and seemed to invade the vena cava below the kidneys. The other intraabdominal organs were normal. A CT scan of the brain revealed two nodules, one in the cor-pus callosum (1 cm) and one in the vermis (2.4 cm). Blood tests showed normal glucose and electrolytes, a creatinine of 56 umol/l (normal range 62–106 umol/l), an elevated lactate dehydrogenase of 1117 U/l (normal range 240–480 U/l) and a suppressed TSH of < 0.01 mU/l (nor-mal range 0.3–3.18 mU/l). The free thyroid hormones were measured and found to be elevated, FT4 was 94.8 pmol/l (normal range 13.1–21.3 pmol/l) and FT3 was 18.2 pmol/l (normal range 4.1–6.7 pmol/l). HCG was massively elevated at 553 627 U/l (normal range < 2 U/l). Urine preg-nancy test was positive. A genital exam, performed after HCG levels were known, did not reveal any testicular masses. DIFFERENTIAL DIAGNOSIS Common endogenous causes of primary hyperthyroidism (suppressed TSH) include Graves’ disease, toxic adenoma, toxic multinodular goitre and thyroiditis (viral or postpar-tum). Rarely, primary hyperthyroidism is caused by germ cell tumours (e.g, choriocarcinoma producing large amounts of HCG) or hyperemesis gravidarum (vomiting and HCG-induced hyperthyroidism in early pregnancy). Very rarely, struma ovarii (ovarian teratoma containing hyperfunction-ing thyroid tissue) may be the cause of hyperthyroidism. Causes of exogenous hyperthyroidism may be contrast agents containing iodine for angiography or CT scans, ami-odarone or overtreatment with thyroid hormone. TREATMENT, OUTCOME AND FOLLOW-UP The patient was diagnosed with a metastatic non-sem-inomatous germ cell tumour on the basis of the mas-sively elevated HCG, the CT scan results and his clinical presentation. A biopsy was not performed. He received the chemotherapy combination BEP (cisplatin, etoposide and bleomycin), to which he responded well. HCG lev-els dropped from 553 627 U/l on presentation to within normal range 5 months after chemotherapy was started. FT4 fell to within normal range within the fi rst 3 weeks ( fi gure 1 ). Unusual association of diseases/symptoms Paraneoplastic hyperthyroidism Sibylle Kohler, 1 Oliver Tschopp, 1 Emanuel Jacky, 2 Christoph Schmid 1 1 Endocrinology Department, University Hospital Zurich, Zurich, Switzerland ; 2 Oncology Department, University Hospital Zurich, Zurich, Switzerland Correspondence to Dr Sibylle Kohler, sibskohler@gmx.ch Summary The authors describe a 31-year-old male with a metastatic germ cell tumour and massively elevated human chorionic gonadotrophin (HCG) levels who presented with hyperthyroidism. As HCG is structurally closely related to thyroid stimulating hormone (TSH), it can activate the TSH receptor; grossly elevated levels may result in hyperthyroidism. After initiation of chemotherapy, HCG levels decreased and hyperthyroidism resolved.
