Irregular heartbeat
Your heart plays a vital part in controlling the health of every other organ in your body, so it’s important that you take good care of it. One easy way to protect your heart is by paying attention to the levels of the thyroid hormone called free thyroxine, or FT4, in your bloodstream. One study published in the journal Circulation found that having unusually high levels of FT4 could be a risk factor for atrial fibrillation, or an irregular heartbeat.