Thyroid function tests is a collective term for blood tests used to check the function of the thyroid. TFTs may be requested if a patient is thought to suffer from hyperthyroidism or hypothyroidism, or to monitor the effectiveness of either thyroid-suppression or hormone replacement therapy.

What is included in a thyroid function test?

The tests included in a thyroid panel measure the level of thyroid hormones in the blood. A thyroid panel usually includes tests for: TSH (thyroid-stimulating hormone) Free T4 (thyroxine) Free T3 or total T3 (triiodothyronine)

What is the best test to check thyroid function?

The best way to initially test thyroid function is to measure the TSH level in a blood sample. Changes in TSH can serve as an “early warning system” – often occurring before the actual level of thyroid hormones in the body becomes too high or too low.