This test determines the amount of free T 4 (also known as free thyroxine) in your blood. To determine how effectively your thyroid gland is operating, you can take a free T 4 test. T4 is one of two hormones generated by the thyroid gland in your neck, which is shaped like a butterfly. T 4 comes in two varieties. Some T 4 in your blood is bound to proteins, whereas other T 4 circulates freely, free of protein binding. Unbound T 4 testing is more accurate than bound T 4 testing. The free T 4 test determines how much T 4 is unbound.
T3 (triiodothyronine) is the other thyroid hormone. T 4 is converted to T 3 and becomes active, affecting the body's tissues. T 3 is also available in two different forms: bound T 3 and free T 3. These hormones aid in the regulation of your body's metabolic rate. Thyroid stimulating hormone (TSH), which is secreted by the pituitary gland in your brain, triggers them into action.
