Endocrine Abstracts

This female patient presented acutely with headache and neck pain associated with vomiting. Neurological examination was normal. Urine pregnancy test prior to imaging was unexpectedly positive. CT head demonstrated a 2.5x1.5 cm hyperattenuating lesion at the left frontoparietal region. Thyroid function tests were in keeping with thyrotoxicosis (TSH <0.01 mU/l, free T4 37.2 pmo/l, free T3 >30.7 pmo/l). Antithyroid medication was commenced and TSH receptor antibody requested. Serum human chorionic gonadotrophin (hCG) was markedly elevated. Ultrasound abdomen identified no evidence of pregnancy, raising the suspicion of an hCG-secreting tumour. CT thorax, abdomen and pelvis identified a right lower lobe subpleural lung mass with bilateral lung nodules and low attenuation lesions of the liver, kidneys and spleen, highly suspicious for metastases. MRI head identified multiple intra-axial enhancing lesions. Liver biopsy histology identified metastatic choriocarcinoma. Unfortunately, the patient deteriorated developing anaemia and haemoptysis. They were rapidly transferred to the specialist quaternary centre and commenced on chemotherapy. Subsequently, they developed multiple sites of haemorrhage (hepatic, renal and pulmonary) and required support with multiple blood product transfusions and critical care admission due to respiratory and haemodynamic compromise. Biochemically, hCG improved dramatically with chemotherapy from a level over 8,000,000 IU/l to 300,000 IU/l. In this context, there was rapid improvement in thyroid function with free T4 levels normalising. HCG-mediated hyperthyroidism is a rare cause of thyrotoxicosis. HCG is a glycoprotein hormone that has intrinsic thyroid-stimulating activity due to structural homology between thyroid stimulating hormone (TSH) and hCG. Anti-thyroid medication can be used to control hyperthyroidism associated with very high levels of hCG. Reducing or normalising hCG levels can quickly induce a euthyroid state. Paraneoplastic hCG secretion is managed with treatment of the underlying malignancy and antithyroid medication. Chemotherapy can lead to a transient elevation in hCG levels and patients should be monitored for thyrotoxicosis or thyroid storm.