Your doctor will ask you about your symptoms, medical history, and family history. A physical exam will be done. Certain tests will be ordered.
Symptoms that could indicate hyperthyroidism include:
- Racing heart or skipped heart beats
- Hand shaking
- Nervousness
- Weight loss
- Heat intolerance (frequently feeling hot)
- Difficulty sleeping
- Irregular periods
- Sweating
- Excessive diarrhea
Physical Exam
The physical exam can reveal:
- An enlarged thyroid gland (called a goiter)
- Bulging eyes
- Increased reflexes
- Fine tremor of the hands
- Muscle weakness
- Rash
- Rapid and irregular pulse
Blood Tests
These tests measure the blood levels of thyroid hormones. If the serum level of thyroid stimulating hormone (TSH) is decreased, and serum free T3, free T4, and free T4 index T3 are elevated, this usually means the thyroid gland is too active. Your blood may also be examined for thyroid antibodies, especially if you are pregnant.
Radioiodine Uptake
This test is used to help define the cause of hyperthyroidism. The thyroid gland uses iodine to make thyroid hormones. For this test, you will orally ingest radioactive iodine. Some of it is taken up by the thyroid gland. The amount of radioactivity is then measured by a radiation counter. In Graves disease, an autoimmune cause of hyperthyroidism, the amount is elevated. This test is not done on children or pregnant women.
Thyroid Scan
This test is occasionally done at the same time as the radioiodine uptake. It helps give a picture of the thyroid and helps help differentiate between Graves disease and other causes of hyperthyroidism. A scan of the thyroid then gives an idea of the size and shape of the thyroid. It can also show small areas of excessive function that may indicate a thyroid nodule. Usually, a thyroid ultrasound is done first to identify any nodules. A thyroid nodule may or may not be functioning and is termed “hot” if it makes too much thyroid hormone, or “cold” if it does not make any.