When the thyroid hormone is elevated, the symptoms may be a tremor, weakness, fatigue, weight loss, a faster heart rate, changes with emotions, or a feeling of anxiety.   Sometimes people with this condition notice a change in the size of the thyroid gland (which is in the front of the neck).

Thyroid function can be measured by laboratory testing.  Blood tests for TSH, T4 and T3 are often used to measure thyroid function.  There are also other tests which can help to measure the structure of the thyroid gland (ultrasound) or its hormone-making function (radio-iodine uptake).

Graves disease is a common cause of hyperthyroidism.  In this condition, the body’s immune system stimulates the thyroid gland to make thyroid hormone.  Other causes of hyperthyroidism include inflammation of the gland and overactive thyroid nodules.