5. High Blood Pressure
An under-active thyroid can raise levels of bad cholesterol, which then triggers high blood pressure, an enlarged heart and, in extreme cases, heart failure.
6. Heart Flutters
Heart flutters can be normal if you’re nervous or scared, but it should be monitored closely.
Irregular heartbeat is a symptom of hyperthyroidism and may lead to more serious heart conditions if left untreated.