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Thyroid Problems (cont.)

Exams and Tests

The medical history and physical exam are important parts of the evaluation for thyroid problems. The doctor will focus on eye, skin, cardiac, and neurologic findings.

Blood tests

Thyroid-stimulating hormone (TSH): In most cases, this is the single most useful lab test in diagnosing thyroid disease. When there is an excess of thyroid hormone in the blood, as in hyperthyroidism, the TSH is low. When there is too little thyroid hormone, as in hypothyroidism, the TSH is high.
Free (T4): T4 is one of the thyroid hormones. High T4 may indicate hyperthyroidism. Low T4 may indicate hypothyroidism.
Triiodothyronine (T3): T3 is another one of the thyroid hormones. High T3 may indicate hyperthyroidism. Low T3 may indicate hypothyroidism.
TSH receptor antibody (TSI): This antibody is present in Grave's disease.
Antithyroid antibody: This antibody is present in Hashimoto and Grave's disease.

Thyroid scan: For this test, a small amount of radioactive iodine is injected into the blood, and then an x-ray image of the thyroid is taken. Increased uptake of the radioactive material in the thyroid gland indicates hyperthyroidism, while decreased uptake is present in hypothyroidism. This test should not be done on pregnant women.

Thyroid ultrasound: This exam helps to differentiate between different types of nodules of the thyroid gland.

Fine-needle aspiration: For this test, a small needle is inserted into the thyroid gland in order to get a sample of thyroid tissue, usually from a nodule. The tissue is then observed under a microscope by a pathologist to look for any signs of cancer.