Graves' disease. Graves' disease is the most common cause of overactive thyroid. It can run in families and can occur at any age, although it is most common in women aged 20-40 years old. You are more likely to develop Graves' disease if you smoke. Graves' disease is an autoimmune condition.
Full Removal. If your doctor removes your entire thyroid, your body will begin to exhibit symptoms similar to hypothyroidism, due to the lack of thyroid hormones in your body. These symptoms may include fatigue, elevated cholesterol levels, uncontrollable weight gain, muscle weakness and depression.
For example, if your body isnât getting enough iodine, your thyroid canât make enough thyroid hormone, but it will try to respond to rising TSH levels by working harder and harder anyway. This can cause your thyroid to become enlarged and develop into a goiter that looks like a protrusion or large swelling in your neck.