This lady 59 yrs with tremors in both hands more since last 8 days. She has exophthalmos since many years but is prominent since last few months. She has profound anxiety and has weight loss since last few months.

O/E:Thin built lady, wt 34kg, short strature, bp 164/70, tachycardia with pulse rate reaching upto 200bpm. How to investigate and manage this patient. What are differential diagnosis?