Most people with Graves' disease have symptoms that are bothersome. If you have symptoms of Graves' disease, your doctor will do an exam and order one or more tests. Tests used to help find out if you have Graves' disease include:

Antibody tests 
A blood sample is sent to a lab to look for antibodies that suggest Graves' disease.

Thyroid function tests
A blood sample is sent to a lab to see if your body has the right amount of thyroid hormone (T4) and TSH. A high level of thyroid hormone in the blood plus a low level of TSH is a sign of overactive thyroid. Sometimes, routine screening of thyroid function reveals mild overactive thyroid in a person without symptoms. In such cases, doctors might suggest treatment or watchful waiting to see if levels return to normal.

Radioactive iodine uptake (RAIU)
An RAIU tells how much iodine the thyroid takes up. The thyroid takes up iodine and uses it to make thyroid hormone. A high uptake suggests Graves' disease. This test can be helpful in ruling out other possible causes of overactive thyroid.

Graves' disease can be hard to diagnose during pregnancy because it has many of the same symptoms as normal pregnancy, like fatigue and heat intolerance. Also, some lab tests can be harder to interpret. Plus, doctors cannot use RAIU during pregnancy to rule out other causes.