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.
Symptom: Hair Loss. Hair loss is another sign that thyroid hormones may be out of balance. Both hypothyroidism and hyperthyroidism can cause hair to fall out. In most cases, the hair will grow back once the thyroid disorder is treated.hen left untreated, hypothyroidism can raise cholesterol levels and make you more likely to have a stroke or heart attack. In severe cases, very low levels of thyroid hormones can trigger a loss of consciousness and life-threatening drop in body temperature.