A 67-year-old man comes for follow-up of coronary artery disease. He is currently feeling well. Three months ago, he was hospitalized for chest pain; coronary angiography revealed 85% narrowing in the mid right coronary artery, and a drug-eluting stent was placed. In addition, TSH was noted to be low. The patient now walks 2-3 miles a day without angina, dyspnea, or lower extremity claudication. He states, "I am very happy that I lost 5 lb since my hospitalization. I also gave up smoking and drinking. I feel like I got my life back." Current medications include aspirin, clopidogrel, metoprolol, lisinopril, and atorvastatin. The patient's father died from a heart attack at age 56, and his mother has osteoporosis and hypertension. Blood pressure is 134/76 mm Hg and pulse is 65/min. BMI is 28 kg/m². Physical examination, including examination of the thyroid gland, is normal. Repeat thyroid function results are as follows: Radioactive iodine uptake is increased, with a homogeneous distribution on thyroid scan. Which of the following is the most appropriate management for this patient?

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Explanation: 11ec2b69_bec9_0c8e_8f63_21a0540033eb_MD0005_00 Subclinical hyperthyroidism is defined as low TSH with normal thyroid hormone concentrations. Transient fluctuations in thyroid markers can be seen (particularly with acute illness), but patients who have persistently suppressed TSH levels warrant further evaluation. This patient has a diffusely increased radioiodine uptake consistent with Graves disease, with worsening of thyroid function test results possibly due to iodinated dye administration during his recent cardiac catheterization. Other common causes of subclinical hyperthyroidism include exogenous thyroid hormone, nodular thyroid disease (thyroid adenoma or toxic multinodular goiter), and inflammatory thyroiditis (eg, silent thyroiditis, subacute [de Quervain] thyroiditis). Severe TSH suppression (<0.1 µU/mL) is associated with a higher risk for progression to overt hyperthyroidism and warrants treatment. Patients with mildly suppressed TSH levels (0.1-0.5 µU/mL) often experience spontaneous remission and can usually be monitored with periodic thyroid function tests. However, those with increased risk for complications due to age (>65) or comorbid conditions (eg, heart disease, osteoporosis) warrant consideration for treatment with antithyroid medication or radioactive iodine. In light of this patient's TSH <0.1 μU/mL, age >65, and comorbid coronary artery disease, treatment should be offered at this time (Choice D). (Choice A) Beta blockers (eg, metoprolol) are used in thyrotoxicosis to control hyperadrenergic symptoms (eg, palpitations, tachycardia). This patient's heart rate is at goal (<70/min) and he is asymptomatic; no increase in dosage is necessary. (Choice C) The diagnosis of Graves disease has been established in this patient by a diffusely increased thyroidal uptake of radioactive iodine. The presence of thyrotropin receptor antibodies is also associated with Graves disease but would not provide any additional information. (Choice E) Ultrasonography is useful for evaluating thyroid nodules but is not required in this patient, who has no palpable nodules and diffuse radioiodine uptake. Educational objective: Subclinical thyrotoxicosis is defined as low TSH with normal thyroid hormone concentrations. Treatment with antithyroid medication or radioactive iodine is warranted for patients who have TSH levels persistently <0.1 µU/mL or who are at increased risk due to age (>65) or comorbid conditions (eg, heart disease, osteoporosis). References: 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. (http://www.ncbi.nlm.nih.gov/pubmed/27521067) Subclinical hyperthyroidism and cardiovascular risk: recommendations for treatment. (http://www.ncbi.nlm.nih.gov/pubmed/23563523)

A 67-Year-Old Man Comes for Follow-Up of Coronary Artery Disease