The measurement of free T4 is mainly used to evaluate disorders of the thyroid gland, usually along with the measurement of thyrotropin hormone (TSH).
Thyroxine (T4) is a hormone produced in the thyroid gland by iodine and thyroglobulin in a multi-step process. Less than 0.05% of thyroxine circulates freely in the serum and is therefore biologically active. Biologically active free thyroxine (FT4) stimulates basic metabolic rate, including carbohydrate and lipid utilization, protein synthesis, bone calcium release, and vitamin metabolism. In infants, thyroxine plays an important role in the development of the central nervous system and in the development. Circulating levels of thyroxine affect the release of TSH and hypothalamic thyrotropin-releasing hormone (TRH) through a negative feedback mechanism.
Possible Interpretations of Pathological Values
• Increase: Hyperthyroidism, acute psychiatric illnesses. Medications: Amiodarone, heparin, propranolol, contrast agents, thyroxine.
• Decrease: Anorexia nervosa, hypothyroidism, after hemodialysis, pregnancy. Medications: Carbamazepine, phenylbutazone, heparin, rifampicin, thiocyanates.
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
