A 56-year-old female was found to have a TSH level of 0.2 iJU/ml on routine lab testing. She denies symptoms suggestive of thyrotoxicosis. She reports good energy level and no change in body weight. She has mild hypertension, for which she is on hydrochlorothiazide. Her family history is negative for any thyroid disorder. She denies smoking or alcohol use. She does not have allergies to any medications. She had her menopause about three 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 six months ago. Examination is unremarkable, including examination of the thyroid gland. FreeT 4 levels and free T3 are well within normal limits. What is the next best step in this patient’s care?
- A. Radioactive iodine uptake [9%]
- B. Start methimazole [1 %]
- C. Start propylthiouracil [1 %] .,
- D. Recheck thyroid functions test in 6-8 weeks [88%]
- E. Subtotal thyroidectomy [1 %]
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Explanation: User ld:
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, 8, C, and E) The above patient did not have any indication for aggressive intervention. In symptomatic patients (e.g. persistent fatigue), an antithyroid drug in a small dose (methimazole 5-10 mg/d) 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 5-1 0%/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 T 4 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.