Hyperthyroid Manifestation in Beta HCG Secreting Tumor

Background: Serum β-Human Chorionic Gonadotropin (HCG) levels can be increased not only in pregnancy but also in various malignancies such as germ cell malignancy, lung cancer, ovarian cancer, and breast cancer. The alpha subunit of HCG and TSH are homologous, so β-HCG can cross-react with the TSH receptors and induce hyperthyroidism. High level of β-HCG serum can lead to hyperthyroidism, which can aggravate the patient’s malignant manifestations. Case Presentation: A 33-year old woman admitted to our hospital with chief complaint general weakness one week before admission. The patient was 8 week-pregnant and the transabdominal ultrasound showed a gestational sac and she had also a positive urine β-HCG test. The patient had slight vaginal bleeding 1 month ago. The physical examination revealed tachycardia, pale conjunctiva, and multiple nodules in both breasts. On laboratory examination, we found low level of Hb 6.7 (n 11.7 - 15.5 g/dl), serum iron 18 (n 65 - 175 mg/dL), TIBC 164 (n 253 - 435 mg/dL), and ferritin 1971(n 4.63-204 mg/dL), positive urine β-HCG, potassium 2.5 (n 3.1 - 5.1 mmol/L). On transvaginal and transabdominal ultrasound examination, there was no gestational sac in the uterine cavity and there are no abnormalities in other gynecology organs. The chest X-ray showed a nodule in the upper right lung suggestive of metastasis with thickening of the soft tissue of the left mammary region suggestive of a left breast mass. We also found a consistent positive result of urine β-HCG, though it had passed four weeks after the occurrence of vaginal bleeding. Finally, the serum β-HCG examination was carried out and showed an increased result, 290,398 (n <5 mIU/ml). The chest CT showed a heterogeny mass (mixed iso-dense and hypodense) that enhanced contrast on the inferior lobe of left lung (4.1 cm x 12.1 cm x 14.1 cm), a mass on apical segment of right lung, subpleural nodule, a mass on the right kidney, spleen, and mediastinal lymphadenopathy. The patient had packed red cell transfusion and after the Hb level reached 11 mg/dl, she still had tachycardia, so we examined the TSHs level. TSHs was found to be low at 0.014 (n 0.48-4.17 mg/dL), and FT4 increased to 2.82 (n 0.89-1.76 mg/dL). Thyroid ultrasound showed small simple cysts in both inferior thyroid pools, no solid mass and no increased vascular flow to the thyroid parenchyma. The patient was then thought to have hyperthyroid manifestation due to β-HCG secreting tumor. She was had methimazole and propranolol therapy, and a lung biopsy was planned. Conclusion: Trophoblastic and non-trophoblastic tumors that secrete high level of β-HCG can induce hyperthyroid manifestations, particularly if the level was more than 20,000 mIU/mL