The ges-
tational age was 4 weeks. Blood examinations revealed negative TSH receptor antibodies, however, we
started potassium iodide because we were unable to rule out Graves’ disease. Thyroid hormone levels were
normalized in 3 weeks and remained low even after discontinuation of medication. She received replacement
therapy with levothyroxine sodium hydrate till 3 months after delivery. Painless thyroiditis can be one of the
differential diagnoses of thyrotoxicosis in a very early stage of pregnancy