About the test
T4 is a hormone produced in the thyroid gland. After its release from the thyroid gland, its biggest part bounds to proteins. The rest of it is called free T4. Free T4 plays a crucial role in the basic metabolic rhythm and protein synthesis.
Sample
Venous blood
Preparation
None required.
In case the examinee is under thyroid medication he/she should postpone intake of medication until after the test
Procedure
Venipuncture
Increased values
- Hyperthyroidism
- Subacute thyroiditis
- Toxic multinodular goiter
- Pregnancy
- Drugs (amiodarone, amphetamines, clofibrate, estrogens, heparin)
Decreased values
- Hypothyroidism
- Hypoalbuminemia
- Thyroidectomy
- Thyroid gland agenesis
- Pituitary tumor
- Drugs (anabolic steroids, aspirin, penicillin, sulphonamides, testosterone)
Additional information
- Thyroxin is essential in the development of the central nervous system in infants.
- T4 measurement is used in the follow-up of thyroid diseases, in patients treated with either synthetic hormones or antithyroid drugs.