A 76-year-old man with recent history of diet control diabetes and hypertension presented to his GP with change in his voice and biochemical T3 toxicosis. He had no further assessment and received no treatment. Few months later he presented with right side goitre and found to have right vocal cord palsy and medullary thyroid cancer and hyperthyroidism. He had evidence of local nodal and distant metastases. Soon after biochemical euthyroidism he underwent total thyroidectomy and local lymph node resection.
Thyroid cancer is occasionally associated with hyperthyroidism. Medullary thyroid carcinoma (MTC) has been rarely described in association with Graves disease or other forms of hyperthyroidism. Careful evaluation of hyperthyroid patients is always necessary to exclude the presence of associated malignancy and to determine the most appropriate therapeutic plan.
A recent study presented at the International Thyroid Congress suggests that endogenous subclinical types of hyperthyroidism may have a larger metabolic effect on insulin resistance than the exogenous type of the condition. While it is obvious that hyperthyroidism does not protect against thyroid cancer but in actual fact can have impact on insulin resistance and probably increasing chance of mutation and thyroid cancer.
The MTC is not common and such presentation like our case is quite rare. However, this case highlights the importance of clinical vigilance and proper assessment of thyroid dysfunction. Furthermore studies are required to explore cause and relationship between thyroid dysfunction, insulin resistance and increase risk of thyroid mutation.