PMC6814060_01
Time course of thyroid function. The first thyrotoxicosis episode was misdiagnosed as Graves' disease and rapidly changed to a hypothyroid state due to thiamazole administration. One and a half years later, a second thyrotoxicosis episode occurred, and the patient recovered without treatment. Four years after the first episode of thyrotoxicosis, the third thyrotoxicosis episode occurred. Low Tc-99 m uptake without fever and pain indicated painless thyroiditis. Retrospectively, all of these thyrotoxicosis episodes seemed to be repeated painless thyroiditis.
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Fig1
The doctor misdiagnosed this thyrotoxicosis episode as Graves' disease without performing an ultrasound examination or confirming the presence of antithyroid antibodies and treated the patient with thiamazole 20 mg. Three months later, the patient showed hypothyroidism (TSH 265.7 muIU/mL and FT4 0.4 ng/dL) (Fig. 1), and the doctor reduced the thiamazole dose.
Thyroid ultrasonography in each phase: (a) the SITSH state, while the patient was hospitalized in August 2015; (b) the third thyrotoxicosis episode in January 2018; and (c) recovery from painless thyroiditis in May 2019. (a) Moderate goiter, slightly heterogeneous hypoechogenicity, and moderately rich thyroid blood flow were detected. (b) There were focal hypoechoic areas without tenderness. (c) The hypoechoic area became invisible, and the echogenicity and homogeneity returned to the original condition
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Fig2
In his usual SITSH state, thyroid ultrasonography showed a moderate goiter, slightly heterogeneous hypoechogenicity, and moderately rich blood flow (Fig. 2a). Thyroid ultrasonography during the third episode of thyrotoxicosis detected a moderate goiter, slightly heterogeneous hypoechogenicity, and moderately rich thyroid blood flow (Fig. 2b). The patient's thyroid function returned to his usual SITSH state without any treatment within 1 month. The hypoechoic area became invisible, and echogenicity and homogeneity returned to the original condition in January 2019, 16 months after the last episode of painless thyroiditis (Fig. 2c).