RESUMEN
Human chorionic gonadotropin (HCG) is one of the glycoproteins families synthesized by the placenta, and consists of 2 noncovalently joined subunits, namely, alpha and beta. The alpha and beta-subunits have a structural homology with the alpha and beta-subunits of TSH and LH. The thyrotropic action of HCG results from its structural similarity to TSH, so beta-HCG can bind to the TSH receptor in the thyroid gland. A high level of HCG, accompanied by an increased thyroid hormone level, can be observed in gestational trophoblastic diseases (GTD), such as a hydatidiform mole or a choriocarcinoma. However, the clinical symptoms of hyperthyroidism in GTD are rarely observed. A 27-years-old woman, admitted due to an amenorrhea of 11 weeks duration, with thyrotoxic symptoms, such as weight loss, palpitation, sweating, tremor, heat intolerance and anxiety, was evaluated. Her serum free T4 level was 8 times higher than normal, and her serum beta-HCG level was over 1,000,000IU/L. She had a curettage operation, with the pathological findings of a complete hydatidiform mole. These thyrotoxic symptoms developed due to a hydatidiform mole, and were accompanied with a highly increased serum beta-HCG level. After evacuation of the molar tissue, the thyroid hormone and thyrotoxic symptoms normalized. Here, this case is reported, with brief review of the literature.