The TSH, or thyroid-stimulating hormone, stimulates your thyroid to release both T3 and T4. Performing one or both of these other tests may help your doctor gain a better understanding of your thyroid problem.
T4 makes up more than 80 of circulating thyroid hormones. Following secretion by the thyroid gland, approximately 70 of circulating T4 and T3 are bound to thyroid-binding globulin (TBG while 10 to 20 each are bound to transthyretin (TTR) and albumin, respectively.
Nelson JC, Clark SJ, Borut DL, et al. Age related changes in serum free thyroxine during childhood and adolescence. J Pediatr. 1993;. Fisher DA. Physiological variations in thyroid hormones; physiological and pathophysiological considerations.
Thyroxine (T4) and triiodothyronine (T3) are the 2 biologically active thyroid hormones. The routine FT4 test (FRT4 / T4 Thyroxine, Free, Serum) is faster and.
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In: Klee. GG, ed. Clinics in Laboratory Medicine: Pathophysiology of Thyroid Disease. Philadelphia, PA: W.B. Saunders Company;. Ross DS. Subclinical hyperthyroidism: possible danger for overzealous thyroxine replacement therapy. Mayo Clin Proc.
Article Resources Article resources Blood Test: T4 (Thyroxine). (2011, April). KidsHealth. org. Retrieved June 1, 2012, from ml T4. (2012, April 18). Lab Tests Online. Retrieved June 1, 2012, from http labtestsonline.
For example, the levels of T3 in your blood might help shed light on the situation. Elevated T4 levels might indicate: hyperthyroidism, such as iodine-induced hyperthyroidism or Graves disease (an autoimmune disease that causes hyperthyroidism) other thyroid problems, such as thyroiditis (inflammation of the thyroid gland) or toxic multinodular goiter (an enlarged thyroid gland with.
Horm Metab Res. 1992;. Refetoff S, Weiss RE, Usala SJ. The syndromes of resistance to thyroid hormone. Endocr Rev. 1993;. Brent GA, Hershman JM, Braunstein GD. Patients with severe nonthyroidal illness and serum thyrotropin concentrations in the hypothyroid range.
Oct 12, 2010. Test, Abbreviation, Typical Ranges. Serum thyroxine, T4, ug/dl. Free thyroxine fraction, FT4F,. Free Thyroxine, FT4, .