Hyperthyroidism is too much thyroid hormone. It is caused by Graves’ disease, toxic goiter (the whole gland is hyperactive), a toxic nodule (single lumps in the thyroid releasing too much hormone), and thyroiditis (inflammation of the gland causing “leakage” of extra hormone). Symptoms include feeling hot while others are cool, weight loss, fatigue, anxiety, fever, diarrhea, irritability, hair loss, tremor, staring gaze, fast heart rate or palpitations, and light periods. It is treated with medicatins that decrease thyroid hormone secretion or decrease its activity in the body. Radioactive iodine treatments can help, and sometimes people require surgery.