Endocrine Abstracts

Introduction: Choriocarcinoma is a rare gynaecological cancer arising from the trophoblastic epithelium of the placenta. HCG induced thyrotoxicosis is a rare but recognised paraneoplastic phenomenon. The association of high BHCG levels and thyrotoxic state is thought to be secondary to similarities in the structure between HCG and pituitary hormones including TSH which share the same alpha unit and enables HCG to activate the TSH receptor at high levels. Kato et al in 2004 reported that the incidence of hyperthyroidism in choriocarcinoma is around 57%. Choriocarcinomas are highly susceptible to treatment with a cure rate of >90% even in metastatic gestational choriocarcinoma.

Case report: A 41-year-old female gravida5 para1, with a history of 4 previous first trimester miscarriages, positive IgM anticardiolipin antibody13 presented to A&E 4 months postnatal with chest pain, palpitations, breathlessness. Blood tests showed B-HCG level > 225, 000, d-dimer -1584, TSH < 0.03 and Free T4-29.1. She was started on carbimazole, propranolol for thyrotoxicosis. Thyroid antibodies were negative. Due to high BHCG values, transabdominal ultrasound was requested which showed no active pregnancy but an increased volume in left ovary. A CTPA with abdominal and pelvic views were negative for a PE but suspicious for pulmonary metastasis and a large left adnexal mass which was confirmed in MRI. The patient was diagnosed with choriocarcinoma, and B-HCG induced thyrotoxicosis and anti-thyroid medication was stopped and patient was commenced on chemotherapy. Her thyrotoxic symptoms were managed symptomatically with propranolol. Following treatment of the Choriocarcinoma, the thyrotoxicosis resolved with normalization of thyroid function tests. (table 1 below)

Discussion: There have been studies in men with germ cell tumours producing HCG, women with choriocarcinoma, animals showing an association between high levels of HCG and hyperthyroidism. The primary treatment for this phenomenon is chemotherapy with symptomatic control for hyperthyroidism. It is important to note that initially the chemotherapy treatment may produce an initial surge in HCG levels, and it is important to monitor these patients for signs of thyroid storm, however, the thyroid function will usually normalise if the choriocarcinoma is susceptible to treatment.

References: 1. Sotello et al. (2016). ‘Choriocarcinoma presenting with thyrotoxicosis’. Proc (Bayl Univ Med Cent).2. Saleem et al. (2021). ‘Metastatic choriocarcinoma in a young woman presenting as a thyroid storm’. J Med Case Reports3. Martinez-Gallegos JC and Ovalle-Zavala EA. (2020).’Thyroid storm associated with testicular choriocarcinoma’. Eur J Case Rep Intern Med.