Subacute Thyroiditis

Abstract

Subacute thyroiditis is a rare inflammatory disease of the thyroid gland. It is believed to be caused by a viral infection, including COVID-19. It accounts for about 5% of all clinical thyroid diseases. Materials and methods. A clinical case of subacute de Quervain's thyroiditis in a patient with diffuse hypermetabolic fixation of 18-fluorodeoxyglucose by the thyroid gland is presented. Results. A 61-year-old patient with no history of thyroid pathology was under observation. 3 weeks after suffering from COVID-19, body temperature began to rise in the evenings from 37.8 to 39.8°C. Moderate pain appeared in the thyroid gland radiating to the lower jaw, severe weakness, tremor of the upper extremities, trembling in the body, weight loss of 12 kg, and sweating were noted. Duration of symptoms is 3 weeks. On palpation, the thyroid gland is enlarged, dense, sharply painful, especially the left lobe. According to ultrasound examination, the iron is enlarged in size, its structure is heterogeneous with extensive hypoechoic areas in both lobes measuring up to 4x7 mm without clear contours. Color Doppler mapping - blood flow is reduced. Combined positron emission and X-ray computed tomography with 18-fluorodeoxyglucose revealed increased diffuse fixation of the radiopharmaceutical in the thyroid gland against the background of an increase in its lobes, SUVmax 10.55. In the blood, the level of thyroid-stimulating hormone is reduced, and free triiodothyronine and thyroxine are increased, the concentration of ferritin is sharply increased - the phenomenon of thyrotoxicosis. A fine needle aspiration biopsy was performed. Cytological examination revealed subacute de Quervain's thyroiditis. Glucocorticoids and non-steroidal anti-inflammatory drugs were prescribed. 4 weeks after treatment, clinical manifestations regressed. Examined after 6 months. According to ultrasound examination, the thyroid gland is not enlarged, the contours are smooth, and with color Doppler mapping, the blood flow is normal. Indicators of thyroid-stimulating hormone, triiodothyronine, thyroxine are within normal limits. Conclusion. The SARS-CoV-2 virus can be regarded as the cause of the development of subacute thyroiditis. According to combined positron emission and X-ray computed tomography with 18-fluorodeoxyglucose, diffuse intense accumulation of the radiopharmaceutical in the thyroid gland was observed. Cytological examination is the basis for differential diagnosis. Glucocorticoids and non-steroidal anti-inflammatory drugs constitute the basic therapy.