Can you die from a high thyroid?

Yes you can. Hyperthyroidism or grave's disease can cause death if untreated. It can affect many organs of the body, but particularly the heart. Arrhythmias, high output failure and changes in the heart size can occur. Psychological issues can arise and many others. This is a very serious condition. In a medically compromised patient or the elderly or one with underlying cardiac dz, it can be very serious.