September 23, 2022
Thyroid Screen 甲状腺检查

Thyroxine (Free T4)

Free T4 is the metabolically active form of thyroxine. This test determines thyroid status, rules out hypothyroidism and hyperthyroidism and evaluates thyroid replacement therapy.


Use of Test: Investigation of thyroid function, as an adjunct to TSH which is the preferred test for assessment of thyroid status. Monitoring patients on thyroid replacement therapy.



Thyroid Stimulating Hormone (TSH)

Hormone synthesis in the thyroid is controlled predominantly by plasma thyroid-stimulating hormone from the anterior pituitary gland. TSH output is regulated by the negative feedback effects of free T3 and free T4 acting on both the hypothalamus and the pituitary. TSH is more sensitive than free T4 to alterations of thyroid status in patients with primary thyroid disease. High levels are found in primary hypothyroidism.


Use of Test: It is the preferred initial test for assessment of thyroid function. Monitoring of patients on thyroid replacement or suppressive therapy.