A 32-year-old woman presents with weight loss of 6.4 kg during the past 8 months and diarrhea of recent onset. Menstruation had ceased 10 weeks earlier. She appears anxious, with pressured speech. Physical examination detects baseline sinus tachycardia, sweaty palms, and a diffusely enlarged thyroid gland. (1+2+5+3+2+2-15)
What is your clinical diagnosis?