A 56-year-old woman was found to have a TSH level of 0.2 μU/mL on routine laboratory testing. She has had no symptoms suggestive of thyrotoxicosis. She reports good energy level and no change in body weight. The patient has mild hypertension, for which she is on hydrochlorothiazide. Family history is negative for any thyroid disorder. She does not use tobacco or alcohol. She does not have allergies to any medications. The patient had her menopause about 3 years ago. She has never received hormone replacement therapy. She takes adequate amounts of calcium and vitamin D supplementation. Bone mineral density using dual photon absorptiometry was within normal range about 6 months ago. Examination is unremarkable, including examination of the thyroid gland. Free T4 levels and free T3 are well within normal limits. What is the next best step in this patient's care?

Question

A 56-year-old woman was found to have a TSH level of 0.2 μU/mL on routine laboratory testing.  She has had no symptoms suggestive of thyrotoxicosis.  She reports good energy level and no change in body weight.  The patient has mild hypertension, for which she is on hydrochlorothiazide.  Family history is negative for any thyroid disorder.  She does not use tobacco or alcohol.  She does not have allergies to any medications.  The patient had her menopause about 3 years ago.  She has never received hormone replacement therapy.  She takes adequate amounts of calcium and vitamin D supplementation.  Bone mineral density using dual photon absorptiometry was within normal range about 6 months ago.  Examination is unremarkable, including examination of the thyroid gland.  Free T4 levels and free T3 are well within normal limits.  What is the next best step in this patient's care?

Quizplus · Accepted Answer

Explanation: The patient has subclinical thyrotoxicosis, which is defined as suppressed TSH levels along with normal thyroid hormone levels. The most common causes of subclinical thyrotoxicosis are treatment with levothyroxine, nodular thyroid disease, Graves' disease, and thyroiditis. Subclinical thyrotoxicosis induced by levothyroxine is simply treated by reducing the dose. In some cases, the etiology cannot be determined, and TSH becomes normal if repeated in a few weeks. Patients who have mildly suppressed TSH, no symptoms, normal heart rhythm, and normal bone density are not intensively investigated because no treatment is necessary, and there is a high chance of normalization of TSH levels. Repeating TSH after 6-8 weeks is generally performed. (Choices A, B, C, and E)This patient did not have any indication for aggressive intervention. In symptomatic patients (eg, persistent fatigue), an antithyroid drug in a small dose (eg, methimazole 5-10 mg/day) is generally started after performing a radioactive iodine uptake and scan. If the symptoms improve with antithyroid drugs, radioactive iodine ablation is usually performed. Patients with multinodular goiter have a 5%-10%/year chance of becoming overtly thyrotoxic; therefore, treatment in such patients is warranted. Patients with atrial fibrillation and low bone densities also require treatment. Educational objective: Patients who have mildly suppressed TSH but normal T4 and T3, no symptoms, normal heart rhythm, and normal bone density are not intensively investigated because no treatment is necessary and there is a high chance of normalization of TSH levels.

A 56-Year-Old Woman Was Found to Have a TSH Level