A 62-year-old woman with primary hypothyroidism has been tre…
A 62-year-old woman with primary hypothyroidism has been treated with levothyroxine (Synthroid) for several months. At a follow-up visit, she reports palpitations, nervousness, insomnia, heat intolerance, and excessive sweating. Her heart rate is 110 beats/min.Recent laboratory results show a suppressed TSH and elevated free T4.Which of the following is the most appropriate next step in management?