A Hispanic female, age 27, has come to the clinic with a complaint of rapid weight loss during the past 6 months despite having a voracious appetite and also that, with the onset of hot weather, she is feeling extreme discomfort. Furthermore, she feels extremely anxious without reporting any severe stressor in her personal life. Her physical exam reveals tachycardia (pulse rate 100 bpm), fine moist skin, a fine tremor, and a symmetrically enlarged thyroid. Further blood work demonstrates elevated free thyroxine ( 10 pmol/l) with TSH at less than 0.2 mlU/l.