Thyroid Function Tests

What are thyroid function tests?

• blood tests - to measure the level of thyroid-stimulating hormone (TSH) in the blood which helps determine thyroid function. High levels of the hormone indicate an underactive thyroid. In addition, a blood test can measure levels of hormones thyroxine (T4) and triiodothyronine (T3), and to measure a protein called thyroxine-binding globulin.ultrasound exam of the thyroid gland - to detect signs of growth and other irregularities. (An ultrasound scan is a diagnostic technique which uses high-frequency sound waves to create an image of the internal organs.)

• thyroid scans using radioactive iodine or technetium (a radioactive metallic element) - to reveal any physical abnormalities of the thyroid.

• functional stimulation tests - tests that help differentiate whether the problem lies with the pituitary gland or the thyroid gland. One such test includes injecting thyrotropin-releasing hormone and measuring the pituitary's response.

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