 A 28-year-old lady visited your office with palpitation, excessive sweating and body weight loss for 7 kg in the last 6 months. She stated that her appetite was good, but she had experienced 2-3 bowel movements a day, and also suffered from oligomenorrhea. Her body height was 166 cm, body weight 46 kg, blood pressure 140/66 mmHg, respiratory rate 24/min, and pulse rate 106/min. She appeared nervous. Skin appeared velvety. Thyroid was mildly enlarged; vascular bruit was audible over neck. Third heart sound was audible over the apex and a grade 2/6 systolic murmur audible along the upper left sternal border. Mild hand tremor was also noted. The rest of the physical examination was normal. What is your tentative diagnosis? What will be your work-up to confirm the diagnosis and what will be your therapeutic plan when the diagnosis is confirmed? (20%)