If your thyroid gland makes too much thyroid hormone, you will have symptoms of . Most hyperthyroidism is caused by an immune system problem called . At first, your hyperthyroidism may make you feel hot, have tremors in your hands, or lose weight. Over time, you may notice that your heart is beating fast, that you feel anxious, or that you are having a lot of bowel movements. You may also feel like you just don't have as much energy as usual.
Hyperthyroidism generally does not go away on its own. Most people need treatment to make hyperthyroidism go away. After treatment, many people develop (too little thyroid hormone).
In rare cases, hyperthyroidism can cause a life-threatening condition called thyroid storm, which develops when the thyroid gland releases large amounts of thyroid hormones in a short period of time. Thyroid storm usually happens after you have had a serious infection or you have been through a stressful time in your life.