What tests are included in thyroid function examinations?

Generally, thyroid function tests include items such as thyroid-stimulating hormone (TSH), total triiodothyronine (TT3), total thyroxine (TT4), free triiodothyronine (FT3), and free thyroxine (FT4). If necessary, these tests should be performed under a doctor's guidance. Detailed explanations are as follows:

1. Thyroid-Stimulating Hormone (TSH)

TSH is a sensitive indicator reflecting the function of the hypothalamic-pituitary-thyroid axis. Its changes occur more rapidly and significantly compared to changes in thyroid hormones. Measuring TSH levels can provide an initial assessment of thyroid function.

2. Total Triiodothyronine (TT3)

TT3 is one of the primary hormones secreted by the thyroid gland and is closely related to thyroid function. In hyperthyroidism, TT3 levels increase, while in hypothyroidism, TT3 levels decrease.

3. Total Thyroxine (TT4)

TT4 is another important hormone secreted by the thyroid gland and serves as one of the most fundamental screening tests for thyroid function. Elevated TT4 levels may be seen in hyperthyroidism, active hepatitis, and other conditions, while decreased levels may indicate other thyroid abnormalities.

4. Free Triiodothyronine (FT3)

FT3 refers to the unbound, free portion of triiodothyronine in the blood and more directly reflects thyroid function. FT3 levels may change during the early stages of hyperthyroidism or at the onset of recurrence, making it one of the preferred tests for diagnosing hyperthyroidism.

5. Free Thyroxine (FT4)

FT4, similar to FT3, represents the unbound, free portion of thyroxine in the blood and is also a sensitive indicator of thyroid function. When combined with TSH testing, it allows for a more accurate assessment of thyroid function.

In daily life, regular thyroid function tests and ultrasound examinations should be performed to detect and treat problems early.