A 71-year-old woman reports fatigue and mild depression. She has hypertension and had a myocardial infarction 4 years ago. She has a family history of autoimmune thyroid disease. The physical examination is unremarkable. No thyroid enlargement is present. Laboratory results include normal levels of hemoglobin, creatinine, and calcium and a normal erythrocyte sedimentation rate. The thyrotropin level is 6.9 mIU per liter (reference range, 0.4 to 4.3), whereas the free thyroxine (T4) level is normal (19 pmol per liter; reference range, 11 to 25). How should she be further evaluated and her symptoms managed?.