A T3 blood test from Walk-In Lab helps evaluate thyroid gland function and in the diagnosis of hyperthyroidism.The Tri-Iodothyronine blood test also goes by T3 Hormone, T3, Total and Total T3. Fasting is not required before taking this test and results are delivered in one to two days. Patients are not required to have insurance or a doctor’s order to purchase this test.Tri-iodothyronine typically represents approximately five percent of the thyroid hormone.Similar to thyroxine, T3 is almost entirely bound to the carrier proteins, with only 0.25 percent of the total being in the free state. When an elevated free, or total thyroxine level is found, measuring T3 can be helpful in confirming the diagnosis of hyperthyroidism. Abnormal total and free tri-iodothyronine concentrations in the presence of normal thyroxine levels, sometimes appear in T3 toxicosis. It is important to note that free T3 levels are not affected by carrier protein variation.