Differences in Clinical and Laboratory Findings Among Graves’ Disease, Painless Thyroiditis and Subacute Thyroiditis Patients With Hyperthyroidism

Background: Graves’ disease, painless thyroiditis and subacute thyroiditis are important in the differential diagnosis for hyperthyroidism in Japan. Methods: We retrospectively picked up patients who had been diagnosed as having hyperthyroidism, at National Center for Global Health and Medicine Kohnodai Hospital, between January 2010 and October 2018. According to the guideline for diagnosis of Graves’ disease, painless thyroiditis and subacute thyroiditis presented by the Japan Thyroid Association, we diagnosed patients as having such diseases. We obtained clinical and laboratory data by using electronic medical records and database after showing the opt-out. Results: Among 91 patients who showed hyperthyroidism, we found 74 patients with Graves’ disease including thyroid storm (n = 5), and seven with painless thyroiditis and 10 with subacute thyroiditis. Graves’ disease patients included a significantly higher percentage of female patients than painless thyroiditis and subacute thyroiditis patients. Serum free triiodothyronine (FT3) level in Graves’ disease patients was significantly higher than that in painless thyroiditis and subacute thyroiditis patients. Serum free thyroxine (FT4) level and the ratio of FT3 to FT4 were significantly higher in Graves’ disease than in painless thyroiditis. The levels of thyroid autoantibodies were significantly higher in Graves’ disease than in other two diseases. Our study showed an increase of white blood cells (WBCs) and percentage of neutrophil in WBC together with a decrease of percentages of lymphocyte and eosinophil in subacute thyroiditis as compared with Graves’ disease and painless thyroiditis. Serum albumin level was significantly lower in subacute thyroiditis patients than in Graves’ disease patients. Serum C-reactive protein (CRP) level was significantly higher in subacute thyroiditis patients than in Graves’ disease patients. Conclusions: Present study elucidated characteristic clinical and laboratory findings for patients with Graves’ disease, painless thyroiditis and subacute thyroiditis who showed hyperthyroidism. J Endocrinol Metab. 2019;9(3):37-42 doi: https://doi.org/10.14740/jem572