Thyroid storm after coronavirus disease 2019 mRNA vaccination in a patient with a history of Graves' disease after coronavirus disease 2019 infection.

We report a case where the patient may have developed Graves' disease after COVID-19 infection, and where the COVID-19 vaccination may have exacerbated the condition, inducing the onset of a thyroid storm. Although any association between the vaccine and the onset of thyroid disease is impossible to demonstrate through a single case, the antecedent COVID-19 infection and COVID-19 messenger ribonucleic acid vaccination may have synergistically contributed to the development of Graves' disease followed by thyroid storm.

Hyperparathyroidism caused by a functional parathyroid cyst.

A 67-year-old Japanese woman was admitted to our hospital for malaise and loss of appetite. Relevant biochemical examinations showed definite hypercalcaemia and elevated serum levels of intact parathyroid hormone (PTH). We performed thyroid ultrasonography and CT of the neck, which revealed a cystic lesion in the right lower lobe of the thyroid glands. Ultrasound-guided fine-needle aspiration was performed, and PTH level of the cystic fluid was markedly elevated. Technetium-99m-hexakis 2-methoxyisobutyi isonitrile sesta scintigraphy showed intense ring-shaped accumulation of radioactivity in the wall of the cyst. The patient underwent a right lobectomy to resect the cystic parathyroid adenoma. After surgery, her serum calcium and PTH level returned to normal ranges.