A 48-year-old woman comes to the clinic for a follow-up visit. Four weeks ago, she was diagnosed with Graves disease after presenting with unintentional weight loss, heat intolerance, and palpitations. At that time, she was initiated on methimazole and propranolol. Today, the patient reports feeling significantly better. She has gained 1.5 kg (3.3 lb) and notes complete resolution of her palpitations and tremors. She denies any sore throat, fever, or abdominal discomfort. Her blood pressure is 120/78 mm Hg and pulse is 74/min. Physical examination reveals a mild, diffuse, non-tender goiter but is otherwise unremarkable. Which of the following is the most appropriate next step in monitoring this patient's treatment?
- Assess free thyroxine and total triiodothyronine concentrationsCevap
- BMeasure serum thyrotropin concentration alone
- CSubstitute methimazole with propylthiouracil to prevent hepatotoxicity
- DAssess prothrombin time and international normalized ratio
- EPerform an electrocardiogram to evaluate for QTc interval prolongation
Cevap
Assess free thyroxine and total triiodothyronine concentrations
The correct action is to assess free thyroxine (FT4) and total triiodothyronine (T3) concentrations. When a patient is initiated on antithyroid drugs (thionamides) like methimazole for Graves disease, circulating thyroid hormones typically begin to normalize within 4 to 8 weeks. However, the pituitary thyrotrophs remain chronically suppressed by the prior long-standing hyperthyroidism. Consequently, serum thyrotropin (TSH) levels remain undetectable or highly suppressed for several months, even after FT4 and T3 have returned to normal. Therefore, initial dose adjustments and treatment monitoring must rely entirely on FT4 and T3 levels.
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Anahtar Kavram
In the initial weeks to months of antithyroid drug therapy for Graves disease, treatment efficacy must be monitored using free thyroxine (FT4) and total triiodothyronine (T3) levels, as serum thyrotropin remains reliably suppressed due to the delayed recovery of the pituitary axis.