When doctor orders blood test of T4... what is T4
Your doctor or endocrinologist will draw your blood in order to test certain hormone levels. He or she may want to measure the thyroid-stimulating hormone (TSH), T3 (triiodothyronine), and T4 (thyroxine) hormone levels. T3 and T4 are the major hormones produced by your thyroid.
Gravesâ Disease Blood Tests. Your doctor or endocrinologist will draw your blood in order to test certain hormone levels. He or she may want to measure the thyroid-stimulating hormone (TSH), T3 (triiodothyronine), and T4 (thyroxine) hormone levels. T3 and T4 are the major hormones produced by your thyroid.