Endocrine Abstracts

Grave’s disease is an autoimmune mediated thyrotoxicosis which accounts for 50–80% of cases of hyperthyroidism. In addition to non-thyroid organ involvement, presence of thyroid stimulating hormone receptor antibodies (TRAb) or increased uptake on a nuclear scan are diagnostic. Ultrasound typically shows a diffuse enlargement of the thyroid with increased vascularity, but up to 23% of patients are known to have thyroid nodules. Thyroid nodules carry a 4–6% risk of malignancy and therefore it is recommendations that patients undergo fine needle aspiration (FNA). Cytology helps differentiate between benign and malignant nodules but may be limited by the quality of the sample. A hemi-thyroidectomy is indicated where FNA fails to resolve uncertainty. Recent studies have indicated a higher risk of thyroid malignancy in individuals with Grave’s disease irrespective of the presence of nodules. We present the case of a 53-year-old female who was referred to clinic with a persistently elevated free triiodithyronine (fT3) 8.3 pmol/l and suppressed thyroid stimulating hormone (TSH) <0.01 mIU/l. This was an incidental finding following a coronary angiogram 5 months earlier. The patient was initiated on carbimazole 5 mg once daily and referred for a Tc99 thyroid uptake scan. She declined the scan, did not attend further appointments and was subsequently discharged from clinic. The carbimazole was stopped 2 years later and the patient remained clinically and biochemically euthyroid off anti-thyroid medication. The patient relapsed the following year with evidence of thyrotoxicosis - TSH <0.01 mIU/l, free thyroxine (fT4) 30.2 pmol/l and fT3 12.1 pmol/l. An ultrasound scan showed a large 5 cm solitary nodule on the right lobe with internal vascularity reported as U3. A nuclear scan showed low uptake in the nodule. FNAC was reported as Thy3a. She was restarted on carbimazole and the local thyroid MDT recommended total thyroidectomy as a definitive treatment for relapsed Grave’s and further assessment of the nodule. Serial repeat TFTs were markedly improved and the carbimazole was gradually reduced and eventually discontinued to reflect this. She has remained biochemically euthyroid. This is an interesting case of a patient with Graves’ disease and an indeterminate thyroid nodule. The risk of thyroid cancer in Graves’ is twice as that of general population and the risk increases to approximately five fold in Grave’s disease patients with thyroid nodules. In patients with a Thy3a nodule, 20–52% will be malignant. The British Thyroid Association (BTA) has subdivided the Thy3 group into Thy3a and Thy3f. They recommend hemi-thyroidectomy for Thy3f and repeat FNA in 3–6 months with MDT discussion for Thy3a.